列表方法的底层实现

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

</body>
<script>
    function List() {
        this.dataStore = [];

        this.append = function () {
            this.dataStore[this.length()] = data;
        }

        this.length = function () {
            //获取数组的长度
            var length = this.dataStore.length;
            return length;
        }

        this.find = function (data) {
            //获得数组的长度
            var length = this.length();
            //设置返回数组的下标
            var index = -1;
            //遍历
            for(var i=0;i<length;i++) {
                if(data==this.dataStore[i]){
                    index = i
                    return index;
                }
            }
            return index;
        }

        this.ForEach = function (call) {
            //获得数组的长度
            var length = this.length();
            //遍历
            for(var i=0;i<length;i++) {
                call(this.dataStore[i]);
            }
        }

        //如果删除成功返回1，失败返回0
        this.remove = function (data) {
            //找到数据所在的位置
            var index = this.find(data);
            if(index==-1)
                return 0;
            //获得数组的长度
            var length = this.length();
            for(var i=index+1;i<length;i++) {
                this.dataStore[i-1] = this.dataStore[i];
            }
            this.dataStore[length-1] = null;
            this.dataStore.length--;
            return 1;
        }

        this.insert = function (data,after) {
            var index = this.find(after);
            if(index==-1) {
                //向队列后面添加数据
                this.append(data);
            }
            else {
                var length = this.length();
                for(var i=length-1;i>index;i--) {
                    this.dataStore[i] = this.dataStore[i+1];
                }
                this.dataStore[index+1] = data;
            }
        }

        this.clear = function () {
            delete this.dataStore;
            this.dataStore = [];
        }

        this.contains = function (data) {

            var iscontains = false;
            this.dataStore.forEach(function (item) {
                if(item == data) {
                    iscontains = true;
                    return;
                }
            });
            return iscontains;
        }

    }

    var list = new List();

    list.append(1);
    list.append(2);
    list.append(3);
    list.append(4);

    list.ForEach(function (data) {
        console.log(data);
    });

</script>
</html>
列表方法的底层实现

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