题目来源
网友@草色遥看的题目
题目描述
实现一个Person，使其输出
new Person('Tom')
.eat('apple')
.sleep(3000)
.play('basketball')
.play('football')
.cancel()
.sleep(3000)
.eat('banana')
/*输出
Tom
apple
(停顿3秒)
basketball
(这里没有football, 因为被下一个方法cancel取消了)
(停顿3秒)
banana
*/
题目考察点
这是一道考察原型、链式调用、事件循环的题目
题目分析
省略n字
题目解答
function Person(name) {
console.log(name || '')
this.fns = []
}
Person.prototype = {
_isMacro: function () {
let len = this.fns.length
return len > 0 && this.fns[len - 1].isMacro
},
_common: function (callback) {
if (this._isMacro()) {
let len = this.fns.length
this.fns[len - 1].callbacks.push(function () {
typeof callback === 'function' && callback()
})
} else {
typeof callback === 'function' && callback()
}
return this
},
eat: function (name) {
return this._common(function () {
console.log(name || '')
})
},
sleep: function (time) {// 开启一个宏任务，并且新建一个任务队列
let _this = this
let timeCount = time || 1000
for (let i = 0; i < _this.fns.length; i++) {
timeCount += _this.fns[i].time
}
let fn = {isMacro: true, callbacks: [], time: timeCount}
this.fns.push(fn)
setTimeout(function () {
console.log(new Date().getTime())
if (_this.fns.length > 0) {
let fn = _this.fns.shift()
for (let i = 0; i < fn.callbacks.length; i++) {
typeof fn.callbacks[i] === 'function' && fn.callbacks[i]()
}
}
}, fn.time)
return this
},
play: function (name) {
return this._common(function () {
console.log(name || '')
})
},
cancel: function () {// 删除某个宏任务中的任务队列中最后一个
if (this._isMacro()) {
let len = this.fns.length
if (len > 0) {
this.fns[len - 1].callbacks.pop()
}
}
return this
}
}
new Person('Tom')
.eat('apple')
.sleep(3000)
.play('basketball')
.play('football')
.cancel()
.sleep(3000)
.eat('banana')
/*输出
Tom
apple
(停顿3秒)
basketball
(这里没有football,因为被下一个方法cancel取消了)
(停顿3秒)
banana
*/
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