第三章 Hodgepodge: 构建可拓展的JavaScript库
作者：互联网
第三章 Hodgepodge: 构建可拓展的JavaScript库
- 3.2 全面的代码组织
- 3.3 创建包
- 3.3.1 构建jscript.array包
- 3.3.2 构建jscript.browser包
- 3.3.3 构建jscript.datetime包
- 3.3.4 构建jscript.debug包
- 3.3.5 构建jscript.dom包
- 3.3.6 构建jscript.form包
- 3.3.7 构建jscript.lang包
- 3.3.8 构建jscript.math包
- 3.3.9 构建jscript.page包
- 3.3.10 构建jscript.storage包
- 3.3.11 构建jscript.string包
- 小结
3.2 全面的代码组织
1. 怎样组织Javascript代码来避免命名冲突，并将相关函数干净地分组在一起？
在JavaScript中，你可以在某种程度上效仿在Java，C#或其他现代语言中使用的包系统。所有你需要做的就是创建一个新的类，然后将所有工具函数作为那个类的成员。
2.
var v = new jscript.ui.alerts();
在java中不行，但在JavaScript中可以，每个函数都是一个类的构造函数，不是创建实例的机制。
jscript = new function(){
return null;
}
var v = new jscript();
v的值为null吗？不。null是jscript所指向的那个函数返回的，而不是那个函数被执行的结果。
3. 如何在警告包里加一个类？比如展示特定信息。
jascript.ui.alerts.MessageDisplayer = function(inMsg){
this.msg = inMsg;
this.toString = function(){
return "msg=" + this.msg;
}
}
var v= new jscript.ui.alerts.MessageDisplayer("Hello!");
alert(v);
这样实际上是在jascript.ui.alerts包中创建了一个名为MessageDisplayer的类。执行到最后两行，创建新的MessageDisplayer的实例，“Hello！”被传给构造函数。当调用alert( )，并传递指向那个实例的变量时，就会调用toString( )函数，我们得到预期结果：弹出信息：“msg=Hello!”。
4. something about import
假设我们想有个叫jsctipt.string的包，希望把这个独立包输入到代码中，可创建这样的文件：
if（typeof jscript == 'undefined'）{
jscript = function(){ }
}
jscript.string = function(){ }
jscript.string.sampleFunction = function(inMsg){
alert(inMsg);
}
为把这些“导入”一个页面：
<script src="jscript.string.js"></script>
（1）如果这是唯一的导入，那么我们就得到一个jscript对象，它包含一个字符串函数，这个字符串函数最后包含sampleFunction函数，所有这些都是在一个层级关系中，最后组成伪包。
（2）更好的做法，如果jscript下面有另外的包，并且我们要导入它们，那么这儿用的if检查语句可以确保每一个包对象总是只有一个副本。
（3）一个最终的好处：如果后来想要扩展包，比如，添加一个jscript.string.format包，我们需要做的就是添加一个新的jscript.string.format.js文件，使用同样的检查方法，再添加一个来检查jscript.string是否已经被定义，如果没有定义就实例化。
（4）目前，用通配符导入足够了，但也可拥有特定类导入的功能：每个单独的包中的每个函数或每个对象放在它自己的.js文件中。
3.3 创建包
3.3.1 构建jscript.array包
1. 如何将一个数组的内容复制到另一个数组
/**
* Copies inSrcArray into inDestArray, appending all the values from inSrcArray
* onto inDestArray.
*
* @param inSrcArray The array to copy FROM.
* @param inDestArray The array to copy TO.
* @return The destination array with the copied elements from the
* source array.
*/
jscript.array.copyArray = function(inSrcArray, inDestArray) {
var i;
for (i = 0; i < inSrcArray.length; i++) {
inDestArray.push(inSrcArray[i]);
}
return inDestArray;
} // End copyArray().
2. 怎样在一个数组中查找指定的元素
/**
* Finds a specified value in an array and returns its position, or -1 if
* the value is not found.
*
* @param inArray The array to search.
* @param inValue The value to look for. Note that the value is search for
* EXACTLY, i.e., case matters, as does whitespace.
* @return The array position the match is found, or -1 if not found.
*/
jscript.array.findInArray = function(inArray, inValue) {
var i;
for (i = 0; i < inArray.length; i++) {
if (inArray[i] == inValue) {
return i;
}
}
return -1;//没查找到的常见返回值
} // End findInArray().
3. 假设我有一个数值的数组，如何计算数组中所有元素的平均值？
/**
* Calculates the average of an array of numeric values. Note that any
* element in the array that is not numeric will likely fowl things up, and
* this IS NOT checked for. It is the caller's responsibility to ensure
* the array contains only numeric values!
*
* @param inArray The array of ONLY numeric values to average.
*/
jscript.array.arrayAverage = function(inArray) {
var accumulator = 0;
var i;
for (i = 0; i < inArray.length; i++) {
accumulator += inArray[i];
}
return accumulator / inArray.length;
} // End arrayAverage().
3.3.2 构建jscript.browser包
如何获取正在使用应用程序的浏览器的标识信息？
/**
* This function returns a string containing identification information
* about the client
*
* @return String of browser identification information.
*/
jscript.browser.getBrowserIdentity = function() {
return navigator.appName + " " + navigator.appVersion;
} // End getBrowserIdentity().
这个代码会返回字符串，它由浏览器的名称和版本组成，比如：
Microsoft Internet Explorer 4.0 ( compatible;MSIE 6.0;Windows NT 5.1; SV1; Maxthon;
WebCloner; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.1)
Microsoft Internet Explorer 部分是navigator.appName( )的结果，剩下的是navigator.appVersion()的结果。
3.3.3 构建jscript.datetime包
1. 怎样知道一个给定月有多少天？
/**
* This function will return the number of days in a given month and year,
* taking leap years into account.
*
* @param inMonth The month, where January = 1 and December = 12.
* @param inYear The year to check the month in.
* @return The number of days in the specified month and year.
*/
jscript.datetime.getNumberDaysInMonth = function(inMonth, inYear) {
inMonth = inMonth - 1;
var leap_year = this.isLeapYear(inYear);
if (leap_year) {
leap_year = 1;
} else {
leap_year = 0;
}
if (inMonth == 3 || inMonth == 5 || inMonth == 8 || inMonth == 10) {
return 30;
} else if (inMonth == 1) {
return 28 + leap_year;
} else {
return 31;
}
} // End getNumberDaysInMonth().
2.怎样判断给定的年份是否为闰年
/**
* This function will determine if a given year is a leap year.
*
* @param inYear The year to check.
* @return True if inYear is a leap year, false if not.
*/
jscript.datetime.isLeapYear = function(inYear) {
if ((inYear % 4 == 0 && !(inYear % 100 == 0)) || inYear % 400 == 0) {
return true;
} else {
return false;
}
} // End isLeapYear().
3.3.4 构建jscript.debug包
1.如何显示任意的一个对象的所有属性及它们的值呢？
/**
* This simple function is one of the handiest: pass it an object, and it
* will pop an alert() listing all the properties of the object and their
* values.
*
* @param inObj The object to display properties of.
*/
jscript.debug.enumProps = function(inObj) {
var props = "";
var i;
for (i in inObj) {
props += i + " = " + inObj[i] + "\n";
}
alert(props);
} // End enumProps().
对每一个属性，我们把它的名字（i的值）和值（使用数组表示法来获取成员）添加到一个字符串中。最后，将字符串传给alert( )，就达到目标了。
2.如何实现一个健壮的自动记录日志机制呢，类似于Jakarta Commons Logging?
可以基于严重级别来记录（或者不记录）日志的日志系统
/**
* This is a very simple logger that sends all log messages to a specified
* DIV.
*/
jscript.debug.DivLogger = function() {
/**
* The following are faux constants that define the various levels a log
* instance can be set to output.
*/
this.LEVEL_TRACE = 1;
this.LEVEL_DEBUG = 2;
this.LEVEL_INFO = 3;
this.LEVEL_WARN = 4;
this.LEVEL_ERROR = 5;
this.LEVEL_FATAL = 6;
/**
* These are the font colors for each logging level.
*/
this.LEVEL_TRACE_COLOR = "a0a000";
this.LEVEL_DEBUG_COLOR = "64c864";
this.LEVEL_INFO_COLOR = "000000";
this.LEVEL_WARN_COLOR = "0000ff";
this.LEVEL_ERROR_COLOR = "ff8c00";
this.LEVEL_FATAL_COLOR = "ff0000";
/**
* logLevel determines the minimum message level the instance will show.
*/
this.logLevel = 3;
/**
* targetDIV is the DIV object to output to.
*/
this.targetDiv = null;
/**
* This function is used to set the minimum level a log instance will show.
*
* @param inLevel One of the level constants. Any message at this level
* or a higher level will be displayed, others will not.
*/
this.setLevel = function(inLevel) {
this.logLevel = inLevel;
} // End setLevel().
/**
* This function is used to set the target DIV that all messages are
* written to. Note that when you call this, the DIV's existing contents
* are cleared out.
*
* @param inTargetDiv The DIV object that all messages are written to.
*/
this.setTargetDiv = function(inTargetDiv) {
this.targetDiv = inTargetDiv;
this.targetDiv.innerHTML = "";
} // End setTargetDiv().
/**
* This function is called to determine if a particular message meets or
* exceeds the current level of the log instance and should therefore be
* logged.
*
* @param inLevel The level of the message being checked.
*/
this.shouldBeLogged = function(inLevel) {
if (inLevel >= this.logLevel) {
return true;
} else {
return false;
}
} // End shouldBeLogged().
/**
* This function logs messages at TRACE level.
*
* @param inMessage The message to log.
*/
this.trace = function(inMessage) {
if (this.shouldBeLogged(this.LEVEL_TRACE) && this.targetDiv) {
this.targetDiv.innerHTML +=
"<div style='color:#" + this.LEVEL_TRACE_COLOR + ";'>" +
"[TRACE] " + inMessage + "</div>";
}
} // End trace().
/**
* This function logs messages at DEBUG level.
*
* @param inMessage The message to log.
*/
this.debug = function(inMessage) {
if (this.shouldBeLogged(this.LEVEL_DEBUG) && this.targetDiv) {
this.targetDiv.innerHTML +=
"<div style='color:#" + this.LEVEL_DEBUG_COLOR + ";'>" +
"[DEBUG] " + inMessage + "</div>";
}
} // End debug().
/**
* This function logs messages at INFO level.
*
* @param inMessage The message to log.
*/
this.info = function(inMessage) {
if (this.shouldBeLogged(this.LEVEL_INFO) && this.targetDiv) {
this.targetDiv.innerHTML +=
"<div style='color:#" + this.LEVEL_INFO_COLOR + ";'>" +
"[INFO] " + inMessage + "</div>";
}
} // End info().
/**
* This function logs messages at WARN level.
*
* @param inMessage The message to log.
*/
this.warn = function(inMessage) {
if (this.shouldBeLogged(this.LEVEL_WARN) && this.targetDiv) {
this.targetDiv.innerHTML +=
"<div style='color:#" + this.LEVEL_WARN_COLOR + ";'>" +
"[WARN] " + inMessage + "</div>";
}
} // End warn().
/**
* This function logs messages at ERROR level.
*
* @param inMessage The message to log.
*/
this.error = function(inMessage) {
if (this.shouldBeLogged(this.LEVEL_ERROR) && this.targetDiv) {
this.targetDiv.innerHTML +=
"<div style='color:#" + this.LEVEL_ERROR_COLOR + ";'>" +
"[ERROR] " + inMessage + "</div>";
}
} // End error().
/**
* This function logs messages at FATAL level.
*
* @param inMessage The message to log.
*/
this.fatal = function(inMessage) {
if (this.shouldBeLogged(this.LEVEL_FATAL) && this.targetDiv) {
this.targetDiv.innerHTML +=
"<div style='color:#" + this.LEVEL_FATAL_COLOR + ";'>" +
"[FATAL] " + inMessage + "</div>";
}
} // End fatal().
} // End DivLogger().
注意在trace( )函数之后，实际上还应该有更多的函数：debug( ), info( ), warn( ), error( ), 和fatal( ), 分别对应每一个日志级别。我省略它们只是为了节约些空间，但它们本质上是trace( )方法，替换掉trace这个名字。
为了达到这个效果，你需要实例化一个DivLogger，如下：
var log = new jscript.debug.DivLogger( );
这个日志记录程序还有另外一个事情要做：调用setTargerDiv( ), 给它传递一个< div >元素的引用，所有日志输出信息都应该写到这里。
然后，调用log.xxxx(yyyy)，xxxx指严重级别（trace, debug, info, warn, error或fatal ）, yyyy指日志信息。也可以调用log.setLevel( )来设置需要记录的信息的级别。例如：
log.setLevel(log.LEVEL_ERROR);
之后，只有LEVEL_ERROR或LEVEL_FATAL级别的信息才记入日志。
3.3.5 构建jscript.dom包
1.如何将任意一个DOM元素居中
/**
* Center a given layer on the screen horizontally.
*
* @param inObj A reference to the element (presumably a layer) to center.
*/
jscript.dom.layerCenterH = function(inObj) {
var lca;
var lcb;
var lcx;
var iebody;
var dsocleft;
if (window.innerWidth) {
lca = window.innerWidth;//内容填充的实际大小
} else {
lca = document.body.clientWidth;//内容填充的实际大小
}
lcb = inObj.offsetWidth;
lcx = (Math.round(lca / 2)) - (Math.round(lcb / 2));
iebody = (document.compatMode &&
document.compatMode != "BackCompat") ?//是否向后兼容
document.documentElement : document.body;
dsocleft = document.all ? iebody.scrollLeft : window.pageXOffset;//dobument.all是否在DOM中出现，出现则IE
inObj.style.left = lcx + dsocleft + "px";
} // End layerCenterH().
2. 如何竖直居中？
/**
* Center a given layer on the screen vertically.
*
* @param inObj A reference to the element (presumably a layer) to center.
*/
jscript.dom.layerCenterV = function(inObj) {
var lca;
var lcb;
var lcy;
var iebody;
var dsoctop;
if (window.innerHeight) {
lca = window.innerHeight;
} else {
lca = document.body.clientHeight;
}
lcb = inObj.offsetHeight;
lcy = (Math.round(lca / 2)) - (Math.round(lcb / 2));
iebody = (document.compatMode &&
document.compatMode != "BackCompat") ?
document.documentElement : document.body;
dsoctop = document.all ? iebody.scrollTop : window.pageYOffset;
inObj.style.top = lcy + dsoctop + "px";
} // End layerCenterV().
3.当使用一个Ajax请求时，得到一堆返回的内容。如果那堆内容中包含一些< script >段，如何执行？
/**
* This function is used to execute all the script blocks found in a
* chunk of text. This is typically used to execute the scripts found in
* an AJAX response.
*
* @param inText The text to parse scripts from to execute.
*/
jscript.dom.execScripts = function (inText) {
var si = 0;
while (true) {
// Finding opening script tag.
var ss = inText.indexOf("<" + "script" + ">", si);
if (ss == -1) {
return;
}
// Find closing script tag.
var se = inText.indexOf("<" + "/" + "script" + ">", ss);
if (se == -1) {
return;
}
// Jump ahead 9 characters, after the closing script tag.
si = se + 9;
// Get the content in between and execute it.
var sc = inText.substring(ss + 8, se);
eval(sc);
}
} // End execScripts().
4. 如何引用任意数量的DOM？
document.getElementById( )来获得一个DOM元素的引用，获得一批元素的引用：
/**
* This function accepts one or more DOM IDs and returns an array which
* contains a reference to all of them. If no arguments are passed in,
* null is returned. If a single ID is passed in, a single element is
* returned. If more than one ID is passed in, an array is passed back.
*
* @param ?? A variable number of arguments, each being a DOM ID to get a
* reference to (or a single ID).
* @return Null is no arguments passed in, or a reference to a single
* DOM element if one ID passed in, or an array of references to
* DOM elements if multiple IDs passed in.
*/
jscript.dom.getDOMElements = function() {
if (arguments.length == 0) {
return null;
}
if (arguments.length == 1) {
return document.getElementById(arguments[0]);
}
var elems = new Array();
for (var i = 0; i < arguments.length; i++) {
elems.push(document.getElementById(arguments[i]));
}
return elems;
} // End getDOMElements().
这个函数接受可变数量的参数，认为它们是DOM元素ID。每个JavaScript函数天生指向一个arguments数组， 也就是传入这个函数的所有参数的数组。
所以，如果没有传入任何参数，这个函数就返回空，它本身是一个非法调用。
传入一个参数， 执行典型的document.getElementById()并返回它。
传入参数不止一个， 循环arguments数组，对每个参数执行document.getElementById()。把调用产生的结果压入到新创建的一个数组， 并且当完成时返回那个数组。数组中每个元素，现在都是指向一个传入的DOM ID的引用。
3.3.6 构建jscript.form包
1. 如何从一个HTML表单生成XML？
/**
* This function takes an HTML form and constructs an XML document from it,
* using the specified root element.
*
* @param inForm A reference ot the HTML form object to serialize.
* @param inRootElement The root element the XML dccument should use.
* @return A string of XML constructed from serializing the
* specified form.
*/
jscript.form.formToXML = function(inForm, inRootElement) {
if (inForm == null) {//接收一个表单inForm的引用
return null;
}
if (inRootElement == null) {//接收一个字符串inRootElement，XML文档根元素的名字
return null;
}
var outXML = "<" + inRootElement + ">";//创建outXML字符串，向它添加根元素
var i;
for (i = 0; i < inForm.length; i++) {//遍历表单的子节点。取得每个节点的类型，名字，值。
var ofe = inForm[i];
var ofeType = ofe.type.toUpperCase();
var ofeName = ofe.name;
var ofeValue = ofe.value;
if (ofeType == "TEXT" || ofeType == "HIDDEN" ||
ofeType == "PASSWORD" || ofeType == "SELECT-ONE" ||//select-one在不是多选时，是你在< select>域中看到的值
ofeType == "TEXTAREA") {//查看类型
outXML += "<" + ofeName + ">" + ofeValue + "</" + ofeName + ">"//向XML字符串中添加一个元素
}
if (ofeType == "RADIO" && ofe.checked == true) {//对于radio域，检查每一个，即使它们全在同一组
outXML += "<" + ofeName + ">" + ofeValue + "</" + ofeName + ">"
}
if (ofeType == "CHECKBOX") {//根据对应项是否被选中而发送值"true"或"false"。
if (ofe.checked == true) {
cbval = "true";
} else {
cbval = "false";
}
outXML = outXML + "<" + ofeName + ">" + cbval + "</" + ofeName + ">"
}
outXML += "";
}
outXML += "</" + inRootElement + ">";
return outXML;
} // End formToXML().
2.如何在< select>域里查找并随意选择一个指定的选项？
找到它并不选择它。
/**
* This function will determine is a select element contains a specified
* option, and optionally will select it.
*
* @param inSelect A reference to the select object to search.
* @param inValue The value to search for.
* @param inJustFind True to just determine if the value exists, false
* to also select it.
* @param inCaseInsensitive If true, the search will ignore case. If false
* only an exact case match will be found.
* @return True if an option with the specified value is
* found in the select, false if not.
*/
jscript.form.selectLocateOption = function(inSelect, inValue, inJustFind,
inCaseInsensitive) {
if (inSelect == null ||
inValue == null || inValue == "" ||
inCaseInsensitive == null ||
inJustFind == null) {
return;
}
if (inCaseInsensitive) {
inValue = inValue.toLowerCase();
}
var found = false;
var i;
for (i = 0; (i < inSelect.length) && !found; i++) {
var nextVal = inSelect.options[i].value;
if (inCaseInsensitive) {
nextVal = nextVal.toLowerCase();
}
if (nextVal == inValue) {
found = true;
if (!inJustFind) {
inSelect.options[i].selected = true;
}
}
}
return found;
} // End selectLocateOption().
3.如何在一个< select>中提供全选功能？
/**
* This function will select all the options in a specified select element.
*
* @param inSelect The select element to select all options in.
*/
jscript.form.selectSelectAll = function(inSelect) {
if (inSelect == null || !inSelect.options || inSelect.options.length == 0) {
return;
}
var i;
for (i = 0; i < inSelect.options.length; i++) {
inSelect.options[i].selected = true;
}
} // End selectSelectAll().
取消选中
/**
* This function will unselect all the options in a specified select element.
*
* @param inSelect The select element to unselect all options in.
*/
jscript.form.selectUnselectAll = function(inSelect) {
if (inSelect == null || !inSelect.options || inSelect.options.length == 0) {
return;
}
var i;
for (i = 0; i < inSelect.options.length; i++) {
inSelect.options[i].selected = false;
}
} // End selectUnselectAll().
3.3.7 构建jscript.lang包
如何获得一个对象的属性并把它们复制给另一个对象？
/**
* This function copies all properties from a source object to a destination
* object, optionally overwriting matching existing members.
*
* @param inSrcObj The object to copy FROM.
* @param inDestObj The object to copy TO.
* @param inOverride If true, any member in the destination object that
* already exists will be overwritten.
* @return The destination object with members copied from the
* source object,
*/
jscript.lang.copyProperties = function(inSrcObj, inDestObj, inOverride){
var prop;
for (prop in inSrcObj) {
if (inOverride || !inDestObj[prop]) {
inDestObj[prop] = inSrcObj[prop];
}
}
return inDestObj;
} // End copyProperties().
3.3.8 构建jscript.math包
如何在一个指定范围内生成随机数？
/**
* This function returns a random integer number within a specified range.
* If the specified minumum is greated than the maximum, zero is returned.
*
* @param inMin The minimum value of the range, inclusive.
* @param inMax The maximum value of the range, inclusive.
* @return A random number within the specified range.
*/
jscript.math.genRandomNumber = function(inMin, inMax) {
if (inMin > inMax) {
return 0;
}
return Math.round(inMin + (inMax - inMin) * Math.random());
} // End genRandomNumber().
3.3.9 构建jscript.page包
1.如何用程序启动对当前页面的打印？
window.print（）,只能在最近的浏览器用。
/**
* This function invokes the browser's print function, if the browser version
* is high enough.
*/
jscript.page.printPage = function() {
if (parseInt(navigator.appVersion) >= 4) {
window.print()
}
} // End printPage().
2.如何使用一个传入页面的参数呢？
/**
* This function returns the value of a specified parameter that may have
* been passed to this page, or it returns an array of all parameters passed
* to the page, depending on the input parameter.
*
* @param inParamName The name of the parameter to get values for, or null
* to return all parameters.
* @return A string value, the value of the specified parameter,
* or an associative array of all parameters if null
* was passed in.
*/
jscript.page.getParameter = function(inParamName) {
var retVal = null;
var varvals = unescape(location.search.substring(1));//获取查询字符串的引用的方法。通过从URL的第２个字符开始，我们可以删除开头的问号，只留下参数。
if (varvals) {
var search_array = varvals.split("&");//把每个参数分隔开，得到一个数组。
var temp_array = new Array();
var j = 0;
var i = 0;
for (i = 0; i < search_array.length; i++) {//遍历数组，每个元素进一步用等号分割，因为每个参数都是一个name=value对
temp_array = search_array[i].split("=");
var pName = temp_array[0];
var pVal = temp_array[1];
if (inParamName == null) {
if (retVal == null) {
retVal = new Array();
}
retVal[j] = pName;
retVal[j + 1] = pVal;
j = j + 2;
} else {
if (pName == inParamName) {
retVal = pVal;
break;
}
}
}
}
return retVal;
} // End getParameters().
所有参数都返回的话，一开始会初始化一个新的数组，向里面添加参数及其值，name,value,name,value等。在处理完参数后，返回这个数组。
3.如何使用JavaScript打破一个框架？
/**
* Call this function to break out of frames.
*/
jscript.page.breakOutOfFrames = function() {
if (self != top) {
top.location = self.location;
}
} // End breakOutOfFrames().
打破框架，只要确保浏览器中的文档也是在顶部的。如果它是一个框架，那就是父框架文档。如果这个文档不是顶部文档，那么我们就把当前文档设置为顶部文档，这通常引发任何的框架被新文档（服务器返回的新结果）重写。
3.3.10 构建jscript.storage包
1.如何创建一个cookie并把它保存在客户端呢？
/**
* Sets a cookie.
*
* @param inName The name of the cookie to set.
* @param inValue The value of the cookie.
* @param inExpiry A Date object representing the expiration date of the
* cookie.
*/
jscript.storage.setCookie = function(inName, inValue, inExpiry) {
if (typeof inExpiry == "Date") {
inExpiry = inExpiry.toGMTString();
}
document.cookie = inName + "=" + escape(inValue) + "; expires=" + inExpiry;
} // End setCookie().
每个cookie有名，值，过期时间。inName,inValue和inExpiry。时间需要GMT日期字符串形式，所以要允许inExpiry可以成为一个实际的Date对象，或者可能是一个GMT日期格式的字符串。
Date对象，调用toGMTString()方法获得适当的格式。然后， 设置document.cookie等于一个字符串，形式：xxxx=yyyy;expires=zzzz，其中xxxx是cookie的名字， yyyy是值，zzzz是日期字符串。
设置另一个cookie，第一个cookie不会被重写。？？？
2.如何获得一个指定cookie的值呢？
/**
* Gets thbe value of a specified cookie. Returns null if cookie isn't found.
*
* @param inName The name of the cookie to get the value of.
*/
jscript.storage.getCookie = function(inName) {
var docCookies = document.cookie;
var cIndex = docCookies.indexOf(inName + "=");
if (cIndex == -1) {
return null;
}
cIndex = docCookies.indexOf("=", cIndex) + 1;
var endStr = docCookies.indexOf(";", cIndex);//每个cookie都有expires=zzzz字符串跟在后面，所以查找分号。
if (endStr == -1) {
endStr = docCookies.length;
}
return unescape(docCookies.substring(cIndex, endStr));
} // End getCookie().
3.如何删除cookie?
/**
* Deletes a cookie.
*/
jscript.storage.deleteCookie = function(inName) {
if (this.getCookie(inName)) {
this.setCookie(inName, null, "Thu, 01-Jan-1970 00:00:01 GMT");
}
} // End deleteCookie().
3.3.11 构建jscript.string包
1.如何计算一个子串在字符串中出现的次数？
/**
* This function searches a string for another string and returns a count
* of how many times the second string appears in the first.
*
* @param inStr The string to be searched.
* @param inSearchStr The string to search for.
* @return The number of times inSearchStr appears in inStr,
* or 0 if inStr or inSearchStr is null or a blank string.
*/
jscript.string.substrCount = function(inStr, inSearchStr) {
if (inStr == null || inStr == "" ||
inSearchStr == null || inSearchStr == "") {
return 0;
}
var splitChars = inStr.split(inSearchStr);
return splitChars.length - 1;//XYZ中找Y，X Z，切成两段，一个Y，所以减一
} // End substrCount().
2.如何从字符串删除指定的字母？或从字符串中删除除了指定字母之外的其他任何字母？
/**
* This function will take take an input string and either strip any
* character that appears in a given list of characters, or will strip any
* character that does NOT appear in a given list of characters.
*
* @param inStr The string to strip characters from.
* @param inStripOrAllow Either the value "strip" or "allow".
* @param inCharList This is either (a) the list of characters that
* will be stripped from inStr (when inStripOrAllow ==
* "strip"), or (b) the list of characters that will
* NOT be stripped from inStr (when inStripOrAllow ==
"allow".
* @return The value of inStr after characters have been
* stripped as specified.
*/
jscript.string.stripChars = function(inStr, inStripOrAllow, inCharList) {
if (inStr == null || inStr == "" ||
inCharList == null || inCharList == "" ||
inStripOrAllow == null || inStripOrAllow == "") {
return "";
}
inStripOrAllow = inStripOrAllow.toLowerCase();
var outStr = "";
var i;
var j;
var nextChar;
var keepChar;
for (i = 0; i < inStr.length; i++) {
nextChar = inStr.substr(i, 1);
if (inStripOrAllow == "allow") {
keepChar = false;
} else {
keepChar = true;
}
for (j = 0; j < inCharList.length; j++) {
checkChar = inCharList.substr(j, 1);
if (inStripOrAllow == "allow" && nextChar == checkChar) {
keepChar = true;
}
if (inStripOrAllow == "strip" && nextChar == checkChar) {
keepChar = false;
}
}
if (keepChar == true) {
outStr = outStr + nextChar;
}
}
return outStr;
} // End stripChars().
3.如果不想改变字符串，只是测试一下是否只包含而合法字符或者只包含非法字符，怎么做？
/**
* This function can check is a given string either only contains characters
* from a list, or does not contain any characters from a given list.
*
* @param inString The string to validate.
* @param inCharList A list of characters that is either (a) the only
* characters allowed in inString (when inFromExcept
* is == "from_list") or (b) the only characters that
* cannot appear in inString (when inFromExcept is
* == "not_from_list").
* @param inFromExcept When this is "from_list", then inString may only
* contain characters from inCharList. When this is
* "not_from_list", then inString can contain any character
* except thos in inCharList.
* @return True if inString only contains valid characters,
* as listed in inCharList when inFromExcept ==
* "from_list", false if not, or true if inString does
* not containt any of the characters listed in
* inCharList when inFromExcept == "not_from_list".
*/
jscript.string.strContentValid = function(inString, inCharList, inFromExcept) {
if (inString == null || inCharList == null || inFromExcept == null ||
inString == "" || inCharList == "") {
return false;
}
inFromExcept = inFromExcept.toLowerCase();
var i;
if (inFromExcept == "from_list") {
for (i = 0; i < inString.length; i++) {
if (inCharList.indexOf(inString.charAt(i)) == -1) {
return false;
}
}
return true;
}
if (inFromExcept == "not_from_list") {
for (i = 0; i < inString.length; i++) {
if (inCharList.indexOf(inString.charAt(i)) != -1) {
return false;
}
}
return true;
}
} // End strContentValid().
4.如何在一个字符串中替换出现的所有某个子串？
/**
* This function replaces a given substring of a string (all occurances of
* it to be more precise) with a specified new substring. The substrings
* can of course be single characters.
*
* @param inSrc The string to replace substring(s) in.
* @param inOld The substring to replace.
* @param inNew The new substring to insert.
* @return The value of inSrc with all occurances of inOld replaced
* with inNew.
*/
jscript.string.replace = function(inSrc, inOld, inNew) {
if (inSrc == null || inSrc == "" || inOld == null || inOld == "" ||
inNew == null || inNew == "") {
return "";
}
while (inSrc.indexOf(inOld) > -1) {
inSrc = inSrc.replace(inOld, inNew);
}
return inSrc;
} // End replace().
5.如何从字符串的开头删掉空格？（左侧，右侧，左右两侧）
/**
* Function to trim whitespace from the beginning of a string.
*
* @param inStr The string to trim.
* @return The trimmed string, or null if null or a blank string was
* passed in.
*/
jscript.string.leftTrim = function(inStr) {
if (inStr == null || inStr == "") {
return null;
}
var j;
for (j = 0; inStr.charAt(j) == " "; j++) { }
return inStr.substring(j, inStr.length);
} // End leftTrim().
/**
* Function to trim whitespace from the end of a string.
*
* @param inStr The string to trim.
* @return The trimmed string, or null if null or a blank string was
* passed in.
*/
jscript.string.rightTrim = function(inStr) {
if (inStr == null || inStr == "") {
return null;
}
var j;
for (j = inStr.length - 1; inStr.charAt(j) == " "; j--) { }
return inStr.substring(0, j + 1);
} // End rightTrim().
/**
* Function to trim whitespace from both ends of a string.
*
* @param inStr The string to trim.
* @return The trimmed string, or null if null or a blank string was
* passed in.
*/
jscript.string.fullTrim = function(inStr) {
if (inStr == null || inStr == "") {
return "";
}
inStr = this.leftTrim(inStr);
inStr = this.rightTrim(inStr);
return inStr;
} // End fullTrim().
6.怎样把一个字符串分割成几个指定长度的片段？
/**
* Breaks a string of text into chunks of a specified size. It will break
* on whitespace only, no mid-word breaks.
*
* @param inText The text to break up.
* @oaram inSize The size of each chunk.
* @return An array containing X number of chunks.
*/
jscript.string.breakLine = function(inText, inSize) {
if (inText == null || inText == "" || inSize <= 0) {//有一个需要切断的字符串，并且还要确认指定的大小大于等于1。
return inText;
}
if (inText.length <= inSize) {//检查inText的大小
return inText;
}
var outArray = new Array();
var str = inText;
while (str.length > inSize) {
var x = str.substring(0, inSize);
var y = x.lastIndexOf(" ");
var z = x.lastIndexOf("\n");
if (z != -1) {
y = z;
}
if (y == -1) {
y = inSize;
}
outArray.push(str.substring(0, y));
str = str.substring(y);
}
outArray.push(str);
return outArray;
} // End breakLine().
小结
本章：如何创建基本的包结构，帮助避免命名空间的冲突，避免过多使用全局变量以及避免到处都是函数。
标签：function,第三章,Hodgepodge,JavaScript,param,jscript,var,return,null 来源： https://blog.csdn.net/qq_43340342/article/details/98492233