js数组 函数 对象

<script type="text/javascript">
        var arr=["张三","中意","李四"];
        var str=arr[0];
        var sub="^i切.割^"
        for (var i = 1; i < arr.length; i++) {
                str=str+sub+arr[i]
        }
        console.log(str)
    </script>

<script type="text/javascript">
        function f1(a,b){
            return a+b
        };
        var f2=function(a,b){
            return a+b
        };
        console.log(f1("函数", "声明"));
        console.log(f2("函数", "表达式"));    
    
</script>
//关于在函数前调用的问题是因为 函数声明提升即解析机制问题 
 
<script type="text/javascript">
                console.log(f1("函数", "声明"));
        console.log(f2("函数", "表达式"));    
        function f1(a,b){
            return a+b
        };
        var f2=function(a,b){
            return a+b
        };
</script>            

<script type="text/javascript">
        function f1(){
            console.log("递归");
            
        };
        f1()
</script>
//同样的将f1放在函数自身内部调用自己如果不添加条件 就会不停的自调用 这就是死递归
<script type="text/javascript">
        function f1(){
            console.log("递归");
            f1()
        };
        
</script>

<script type="text/javascript">
        
    var arr = [1, 2, 3, 4, 5];
    console.log(arr);
    console.log(arr.valueOf());
    console.log(arr.toString());
    console.log(arr.join());
    console.log(arr.join("-"));
    console.log(arr.join(""));
    //检测数组
    console.log(arr instanceof Array);//true
    //console.log({} instanceof Array);//false
    console.log(Array.isArray(arr));//true
    //console.log(Array.isArray({}));//false


    </script>

    var arr = [1, 2, 3, 4, 5];
    console.log(arr);
    //console.log(arr.push(0));//从后面添加元素 返回新数组的长度
    //console.log(arr.pop());//从后面删除元素 返回被删除的元素
    //console.log(arr.shift());//从前面删除元素 返回被删除的元素
    //console.log(arr.unshift(0));//从前面添加元素 返回新数组的长度
    console.log(arr);

    //将一个字符串数组输出为用|分割的字符串，如 ["1", "2", "3"] 变为 "1|2|3"。（两种方式）
    var arr = ["1", "2", "3"];
    /*function join(arr, sep) {
     var str = arr[0];
     for (var i = 1; i < arr.length; i++) {
     str = str + sep + arr[i];
     }
     return str;
     }
     console.log(join(arr, "|"));*/
    console.log(arr.join("|"));

    //将字符串数组的顺序进行反转。["a","b","c","d"]变为["d","c","b","a"]。（三种方式）
    var arr = ["a", "b", "c", "d"];
    console.log(arr);
    /*function reverse(arr) {
     var newArr = [];
     for (var i = arr.length - 1; i >= 0; i--) {
     newArr.push(arr[i]);
     }
     //console.log(newArr);
     return newArr;
     }
     console.log(reverse(arr));*/
    /*function reverse(arr) {
     for (var i = 0; i < arr.length / 2; i++) {
     //0 arr.length-1-0
     //1 arr.length-1-1
     //2 arr.length-1-2
     //i arr.length-1-i
     var temp = arr[i];
     arr[i] = arr[arr.length - 1 - i];
     arr[arr.length - 1 - i] = temp;
     }
     //console.log(arr);
     return arr;
     }
     console.log(reverse(arr));*/
    //console.log(arr.reverse());