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前端学习记录

2021-12-05 20:04:01 作者：互联网

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

</head>
<body>

</body>
</html>
<script>
    var arr1=[1,2,3,4]
    var arr2=['a','b','c',3214,351,{name:'xiaoming'
    ,age:12,hobbies:['英雄联盟','王者荣耀']}
    ,[1,2,3]]
    var arr3 = new Array(9,3,0)
    console.log(arr3)
    var arr4 = []//推荐这样使用更简单
    console.log(arr2.length)
    console.log(arr3.length)
    arr2[2]='d'
    console.log(arr2)
    arr3=[11]='arr3d'
    console.log(arr3)

    console.log(arr1)
    arr1.push('d')
    console.log(arr1)
    arr1.pop()//从最后删除
    console.log(arr1)
    arr1.shift()//从前面删除
    console.log(arr1)
    arr1.unshift(0)//从前面增加
    console.log(arr1)
    console.splice(1,0,'a','b')
    console.log(arr1)//任何位置增加删除

    //typeof
    var a=1 ,b='1' , c=true,d=null
    console.log(typeof a)  //语法糖
    console.log((e.length))
    if(typeof e=="object"&&(e.length||e.length==0)){
        console.log('e is Array')

    }
    console.log(Array.isArray(e))
    //if (Array.isArray(e)){
    //console.log('是数组')
    //}else{
    //  console.log('不是数组')
    //}

</script>

标签：console,log,记录,前端,学习,length,arr3,arr1,var
来源： https://www.cnblogs.com/huzhibolibrary/p/15646864.html