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類中調用間隔時的錯誤回調

JavaScript

哈士奇WWW 2023-04-27 10:08:03

我正在嘗試在我的 js 類中創建間隔，代碼如下所示：class Clock {constructor(template) { this.template = template; this.timer = this.timer; this.date = new Date(); // call date}render = () => { let hours = this.date.getHours(); // get hours if (hours < 10) hours = '0' + hours; let minutes = this.date.getMinutes(); // get minutes if (minutes < 10) minutes = '0' + minutes; let seconds = this.date.getSeconds(); // get seconds if (seconds < 10) seconds = '0' + seconds; let output = hours + ':' + minutes + ':' + seconds; return output; // output}stop = () => { // stop interval clearInterval(this.timer);}start = () => { // start interval this.timer = setInterval(this.render(), 1000);}}var clock = new Clock({template: ''});clock.start();我有這樣的錯誤：TypeError [ERR_INVALID_CALLBACK]: Callback must be a function. Received '06:16:49'at setInterval (timers.js:166:3)at Clock.start (/home/runner/Training/index.js:28:20)at /home/runner/Training/index.js:33:7at Script.runInContext (vm.js:130:18)at Object.<anonymous> (/run_dir/interp.js:209:20)at Module._compile (internal/modules/cjs/loader.js:1137:30)at Object.Module._extensions..js (internal/modules/cjs/loader.js:1157:10)at Module.load (internal/modules/cjs/loader.js:985:32)at Function.Module._load (internal/modules/cjs/loader.js:878:14)at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)我認為問題是當我打電話this.timer = setInterval(this.render(), 1000);但是當我更改為錯誤this.timer = setInterval(this.render, 1000);時會顯示這樣javascript。所以任何人都可以幫助我。謝謝。

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4 回答

慕尼黑5688855

TA貢獻1848條經驗獲得超2個贊

您的代碼存在一些問題，但請嘗試以下操作：

class Clock {

constructor(template) {

this.template = template;

this.date = new Date(); // call date

}

render() {

let hours = this.date.getHours(); // get hours

if (hours < 10) hours = "0" + hours;

let minutes = this.date.getMinutes(); // get minutes

if (minutes < 10) minutes = "0" + minutes;

let seconds = this.date.getSeconds(); // get seconds

if (seconds < 10) seconds = "0" + seconds;

let output = hours + ":" + minutes + ":" + seconds;

return output; // output

}

stop() {

// stop interval

clearInterval(this.timer);

}

start() {

// start interval

this.timer = setInterval(() => this.render(), 1000);

}

const clock = new Clock("");

clock.start();

您的構造函數設置不正確（但也未使用）并且您的this引用已關閉。

實時示例： https ://codesandbox.io/s/clock-test-1r8dm?file=/src/index.js

根據 OP 的評論，OP 可能要求增加時間。如果是這樣，請將渲染替換為

render() {

const nD = new Date();

let hours = nD.getHours(); // get hours

if (hours < 10) hours = "0" + hours;

let minutes = nD.getMinutes(); // get minutes

if (minutes < 10) minutes = "0" + minutes;

let seconds = nD.getSeconds(); // get seconds

if (seconds < 10) seconds = "0" + seconds;

let output = hours + ":" + minutes + ":" + seconds;

return output; // output

}

反對回復 2023-04-27

滄海一幻覺

TA貢獻1824條經驗獲得超5個贊

setInterval 接受函數的名稱

class Clock {

constructor(template) {

this.template = template;

this.timer = this.timer;

this.date = new Date();

}

render = () => {

let time = this.date;

let hours = time.getHours();

if (hours < 10) hours = "0" + hours;

let minutes = time.getMinutes();

if (minutes < 10) minutes = "0" + minutes;

let seconds = time.getSeconds();

if (seconds < 10) seconds = "0" + seconds;

let output = hours + ":" + minutes + ":" + seconds;

console.log(output);

}

stop = () => {

clearInterval(this.timer);

}

start =() => {

this.timer = setInterval(this.render, 1000);

}

var clock = new Clock({ template: "" });

clock.start();

反對回復 2023-04-27

動漫人物

TA貢獻1815條經驗獲得超10個贊

setInterval需要一個回調函數。你不應該執行它。

start =() => {

this.timer = setInterval(() => this.render(), 1000);

}

class Clock {

constructor(template) {

this.template = template;

this.timer = this.timer;

// this.date = new Date(); // call date

}

render = () => {

const date = new Date();

let hours = date.getHours(); // get hours

if (hours < 10) hours = '0' + hours;

let minutes = date.getMinutes(); // get minutes

if (minutes < 10) minutes = '0' + minutes;

let seconds = date.getSeconds(); // get seconds

if (seconds < 10) seconds = '0' + seconds;

let output = hours + ':' + minutes + ':' + seconds;

console.log(output)

return output; // output

}

stop = () => { // stop interval

clearInterval(this.timer);

}

start = () => { // start interval

this.timer = setInterval(this.render, 1000);

}

var clock = new Clock({ template: '' });

clock.start();

反對回復 2023-04-27

德瑪西亞99

TA貢獻1770條經驗獲得超3個贊

setInterval 創建了一個新范圍，所以this在 setInterval 內部不是同一個類實例，所以this.date.getHours()會拋出錯誤，因為this.datewill undefined。

反對回復 2023-04-27

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