函数的链式调用实现Man().sleep().eat()

let index = 0;
let stack = [];
function next() {
let fn = stack[index];
index++;
if(typeof fn === 'function'){
fn();
}
}
function fn1() {
console.log(1)
next()
}
function fn2() {
setTimeout(function() {
console.log(2)
next()
},0)
 
}
function fn3() {
console.log(3)
next()
}


// stack.push(fn1)
// stack.push(fn2)
// stack.push(fn3)
function Man(name) {
    stack.push(function(){
        console.log(name);
        next();
    })
}
var LazyMan = function(name) {
    return new Man(name)
}
Man.prototype.sleep = function(time){
 
    stack.push(function(){
        setTimeout(function() {
            console.log(time + '秒')
            next()
        },time *1000)
    })
    return this;
}
Man.prototype.eat = function(food){
 
        stack.push(function(){
            console.log('eat '+food)
            next();
        })
        return this;
}
Man.prototype.sleepFirst = function(time){
    stack.unshift(function(){
        setTimeout(function() {
            console.log('wake up after '+ time + '秒')
            next()
        },time *1000)
    })
    return this;
}




// LazyMan('Hank')




/* 输出:




Hi! This is Hank!




*/




// LazyMan('Hank').sleep(1).eat('dinner')




/* 输出:




Hi! This is Hank!




// 等待10秒..




Wake up after 10




Eat dinner~




*/




// LazyMan('Hank').eat('dinner').eat('“supper”')




/* 输出:




Hi This is Hank!




Eat dinner~




Eat supper~




*/




LazyMan('“Hank”').sleepFirst(2).eat('“supper”')




/* 等待5秒，输出




Wake up after 5




Hi This is Hank!




Eat supper




*/
// console.log(stack[0]())
next()