链式调用 其实就是把本身的值返回出去，供下次调用使用。

    1. <!DOCTYPE html>
    2. <html lang="en">
    3. <head>
    4.     <meta charset="UTF-8">
    5.     <meta name="viewport" content="width=device-width, initial-scale=1.0">
    6.     <title>链式调用</title>
    7. </head>
    8. <body>
    10. </body>
    11. </html>
    12. <script>
    13.     function Person(){
    14.         this.value = '前,端,伪,大,叔';
    15.     }
    16.     Person.prototype.split = function () {
    17.         return this.value.split(',');
    18.     }
    20.     Person.prototype.reverse = function () {
    21.         if(!Array.isArray(this.value)) return 'not Array'
    22.         this.value.reverse();
    23.         return this;
    24.     }
    26.     const ming = new Person();
    27.     console.log(ming.split());              //  (5) ["前", "端", "伪", "大", "叔"]
    28.     console.log(ming.split().reverse());    //  (5) ["叔", "大", "伪", "端", "前"]
    29.     console.log(ming.reverse());            //  not Array
    30.     console.log(ming.value);                //  前,端,伪,大,叔
    31. </script>