With the continuous development of Internet technology, front-end technology is changing with each passing day, and various development frameworks have sprung up. Among them, Vue, as a newcomer in the field of front-end development, has won the favor of the majority of developers because of its lightweight and easy-to-use characteristics.
In Vue, there is a very practical function-time-lapse shooting, which can make our code more efficient and elegant. This article will introduce in detail how to use the time-lapse shooting function in Vue.
1. Vue’s timer
The timer in Vue is a very practical tool that allows us to perform certain operations within a specific time interval. In Vue, timers are implemented through two functions: setTimeout and setInterval.
- setTimeout function
The setTimeout function refers to executing a piece of code after the specified time. The basic syntax is as follows:
setTimeout(function() {
//执行要延迟执行的代码
}, 延迟时间);Copy after login
Among them, the delay time is in milliseconds, indicating how many milliseconds after which the code to be delayed is executed.
For example, if we want to output "Hello World" after 1 second, we can write like this:
setTimeout(function() {
console.log("Hello World");
}, 1000);Copy after login
- setInterval function
The setInterval function refers to each Execute a piece of code at certain intervals. The basic syntax is as follows:
setInterval(function() {
//执行要周期执行的代码
}, 周期时间);Copy after login
Among them, the cycle time is in milliseconds, indicating how many milliseconds the code to be executed periodically is executed.
For example, if we want to output "Hello World" every 1 second, we can write like this:
setInterval(function() {
console.log("Hello World");
}, 1000);Copy after login
2. Vue's time-lapse shooting function
Time-lapse in Vue The shooting function is very practical in actual development. It can perform certain operations within a specific time. For example, after the user completes input, delaying for a period of time before requesting the interface can effectively reduce the load on the server and improve application performance. Let’s take a look at how to use the time-lapse shooting function in Vue.
In Vue, the time-lapse shooting function can be implemented using the watch depth observation mechanism provided by Vue. When we want to listen to a property, Vue will automatically trigger the callback function when the value of the property changes.
- The basic syntax of time-lapse shooting
The basic syntax of time-lapse shooting is as follows:
watch: {
属性名: {
handler: function (val) {
setTimeout(function() {
console.log('值已经改变了，新值为：' + val);
}, 延迟时间);
},
deep: true,
},Copy after login
Among them, whenever the value of the attribute name changes , the function will be automatically called and the code we defined will be executed after the specified delay time.
The deep attribute indicates the hierarchical depth of the attribute to be observed. If set to true, all sub-properties of the attribute will be monitored. If set to false, only the direct sub-properties of the attribute will be monitored. If the deep attribute is not set, it defaults to false.
For example, if we want to monitor name changes and output "Your name has changed" 1 second after the name changes, we can write like this:
watch: {
name: {
handler: function (val) {
setTimeout(function() {
console.log('您的名字已经改变');
}, 1000);
},
deep: true,
},
}Copy after login
- Time-lapse shooting Application Example
The following is a practical application example. After we finish typing in the search box, we delay for 1 second before requesting the interface to obtain the search results. The code is as follows:
<template>
<div>
<input type="text" v-model="searchText" @input="handleInput">
<div v-if="searchResults.length > 0">
<ul>
<li v-for="item in searchResults">{{ item }}</li>
</ul>
</div>
</div>
</template>
<script>
export default {
data() {
return {
searchText: '',
searchResults: [],
}
},
watch: {
searchText: {
handler: function (val) {
setTimeout(() => {
this.search();
}, 1000);
},
deep: true,
},
},
methods: {
search() {
//在此处发去请求获取搜索结果
this.searchResults = ['搜索结果1', '搜索结果2'];
},
handleInput() {
this.searchResults = [];
},
},
}
</script>Copy after login
In the above code, we sent a request in the search method, obtained the search results, and displayed the results on the page. When the value in the user input box changes, the search is delayed for 1 second to reduce the load on the server.
3. Summary
The time-lapse shooting function in Vue can help us execute code within specific time intervals in actual development, thereby improving application performance and code maintainability. The implementation of time-lapse shooting needs to be implemented through Vue's watch depth observation mechanism, and the appropriate delay time and callback function can be set. During the development process, we can flexibly apply it according to actual needs, making our code more efficient and elegant.
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