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做点记录和总结吧,关于js中数组的函数方法

时间:2019-09-05 21:54:48      阅读:118      评论:0      收藏:0      [点我收藏+]

1 length:长度

<script>
 var arr = [1,2,3,4,5,6,7,8];
    console.log(arr.length);//arr.length = 8;
    arr.length = 5;//给定数组长度;
    console.log(arr);//arr = [1,2,3,4,5];
    delete arr[2];//删除arr[2],数组长度不变;
    console.log(arr);//arr = [1, 2, empty, 4, 5];
    console.log(typeof(arr[2]));//undefined;
    console.log(arr.length);
</script>

2 pop,push:方法,把数组相当于一个栈

push(x):向数组尾部压入x,并返回新数组的长度

pop():从尾部弹出一个元素,并返回弹出的元素

  <script>
    var arr = [1,2,3,4,5];
    var number = arr.push(7);//arr.push(9) 相当于 arr[arr.length] = 7;
    console.log(arr);//arr = [1,2,3,4,5,7]
    console.log(number);//6
    var num = arr.pop();
    console.log(arr);// arr = [1,2,3,4,5]
    console.log(num);//7
  </script>

3 unshift 和 shift 方法,把数组相当于一个队列

unshift(x):向数组头部插入x,并返回数组长度

shift():从头部弹出一个元素,并返回弹出的元素

  <script>
    var arr = [1,2,3,4,5];
    var number = arr.unshift(9);
    console.log(arr);// arr = [9,1,2,3,4,5];
    console.log(number);// 6
    var num = arr.shift();
    console.log(arr);// arr = [1,2,3,4,5];
    console.log(num);//9
  </script>

4 slice 和 splice 方法

slice(x,y):返回数组[x,y),索引位置的片段,左从0开始,右从-1开始,不影响原数组

splice(x,y,[.....]):x:删除的起始位置,y删除的个数(没有y的话,删除起始点开始所有),[...]为要插入数组的所有参数;splice方法改变原数组

 <script>
    var arr = [1,2,3,4,5];
    console.log(arr.slice(1,3));//[2, 3]
    console.log(arr);// [1,2,3,4,5]
    console.log(arr.slice(1));//[2, 3, 4, 5]
    console.log(arr.length);//5
    console.log(arr.slice(0,-1));//[1, 2, 3, 4]
    var arr1 = [1,2,3,4,5,6];
    console.log(arr1.splice(1,2));//[2, 3]
    console.log(arr1);//[1, 4, 5, 6]
    console.log(arr1.splice(0));//[1, 4, 5, 6]
    console.log(arr1);//[]
    arr1 = [1,6]
    console.log(arr1.splice(0,1,1,2,3,‘4‘,‘5‘));//[1]
    console.log(arr1);//[1, 2, 3, "4", "5", 6]
  </script>

待后续补充........

 

做点记录和总结吧,关于js中数组的函数方法

原文:https://www.cnblogs.com/Zxq-zn/p/11469824.html

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