There are two types of timers in js, one is to execute setInterval cyclically, and the other is to execute setTimeout periodically.
Note: The timer needs to be cleared when the page is destroyed, otherwise it will always exist!
1. Loop execution (setInterval)
As the name implies, loop execution is to set a time interval, and this method will be executed in a loop every time until the timer is destroyed;
syntax :
setInterval(code, milliseconds)；
setInterval(function, milliseconds, param1, param2, ...)；
code/function 必需。要调用一个代码串，也可以是一个函数。
milliseconds 必须。周期性执行或调用 code/function 之间的时间间隔，以毫秒计。
param1, param2, ... 可选。 传给执行函数的其他参数（IE9 及其更早版本不支持该参数）。
返回值: 返回一个 ID（数字），可以将这个ID传递给 clearInterval() 来取消执行。
eg: At the
beginning, a timer setInterval was created with a time interval of 2 seconds. The function valChange will be called every 2 seconds to make the value of value +1.
<template>
<div>
<h1>{
{
value}}</h1>
<el-button type="primary" @click="start">开始</el-button>
<el-button type="danger" @click="over">结束</el-button>
</div>
</template>
<script>
export default {
data() {
return {
timer: "",
value: 0,
};
},
methods: {
start(){
this.timer = setInterval(this.valChange, 2000); // 注意: 第一个参数为方法名的时候不要加括号;
},
valChange() {
this.value++;
console.log(this.value);
},
over(){
clearInterval(this.timer);
}
},
mounted() {
},
beforeDestroy() {
clearInterval(this.timer);
},
};
</script>
effect:
2. Timed execution (setTimeout)
Timed execution of setTimeout is to set a time, and only execute once when the waiting time is reached , but after the execution, the timer is still there, but it is no longer running;
syntax :
setTimeout(code, milliseconds, param1, param2, ...)
setTimeout(function, milliseconds, param1, param2, ...)
code/function 必需。要调用一个代码串，也可以是一个函数。
milliseconds 可选。执行或调用 code/function 需要等待的时间，以毫秒计。默认为 0。
param1, param2, ... 可选。 传给执行函数的其他参数（IE9 及其更早版本不支持该参数）。
返回值: 返回一个 ID（数字），可以将这个ID传递给 clearTimeout() 来取消执行。
eg:
Create a timer setTimeout at the beginning, and execute the method only after 2 seconds.
<template>
<div>
<h1>{
{
value}}</h1>
<el-button type="primary" @click="start">开始</el-button>
</div>
</template>
<script>
export default {
data() {
return {
timer: "",
value: 0,
};
},
methods: {
start(){
this.timer = setTimeout(this.valChange, 2000); // 注意: 第一个参数为方法名的时候不要加括号;
},
valChange() {
this.value++;
console.log(this.value);
}
},
mounted() {
},
beforeDestroy() {
clearTimeout(this.timer);
},
};
</script>
effect:
