javaScript链式调用

// 链式调用
    const line = {
        init(val){
            this.val = val;
            return this;
        },
        add(next){
            this.val += next;
            return this;
        },
        value(){
            let temp = this.val;
            this.val = null;
            return temp;
        }
    }
    console.log(line.init(5).value())
    return ""+line.init(5).add(5).value()