Simulating Delay using jQuery and setTimeout()

Simulate event delay, such as simulation results loading before displaying them on the page. This example uses recursive setTimeout() to call a function that iterates over an array of pre-checked results to check JavaScript, Flash, browser versions, and more. I will write it into a jQuery plugin later when I have time, which is easy, just determine what options to provide to meet different usage situations .

Demo

jQuery Code (Recursive setTimeout())

// 数据和设置
var result = '预检查通过。', // 主结果的 HTML
    delay = 500, // 子结果的延迟
    data = [
    'Javascript ',
    '系统 ',
    '设备 ',
    '浏览器 ',
    'Flash '
    ];

// 从数组索引 0 开始的自执行函数
(function process_els(el_index) {
    var el = data[el_index],
        precheckUl = $('#precheck ul'),
        loadingLi = $('<li class="loading">正在加载...</li>'), // 创建加载项
        sysPreId = "syspre_" + el_index;

    // 显示加载图像
    precheckUl.append(loadingLi.clone().attr("id", sysPreId));

    // 模拟延迟后，将加载图像替换为子检查结果
    setTimeout(function() {
        precheckUl.find('li.loading:first').replaceWith('<li>' + data[el_index] + '检查完成</li>'); // 添加检查完成状态
    }, delay);

    // 模拟延迟，递归调用自身，直到所有数组元素都已处理
    if (el_index + 1 < data.length) {
        setTimeout(function() { process_els(el_index + 1); }, delay);
    } else {
        setTimeout(function() {
            // 在所有子检查都插入后追加最终结果
            precheckUl.after('<p>' + result + '</p>');
        }, (delay * 2));
    }
})(0);

HTML

<div id="precheck">
  <h2>系统检查</h2>
  <ul></ul>
</div>

Frequently Asked Questions about Using setTimeout Analog Delay (FAQ)

Why use setTimeout in JavaScript?

setTimeout is a method in JavaScript that allows you to schedule a function or specific block of code to run after delay. This is a way to delay the execution of a function. This is useful in various situations, such as creating animations, delaying alerts, or making a function wait for certain data.

setTimeout How does it work?

setTimeout Works by taking two parameters: a function and a delay in milliseconds. When you call setTimeout, it starts a timer. Once the timer reaches the specified delay, it executes the function. It should be noted that setTimeout will not pause the execution of the remaining code. It just arranges the function to run later.

Can I cancel setTimeout?

Yes, you can use the clearTimeout function to cancel setTimeout. When you call setTimeout, it returns a unique ID. You can pass this ID to clearTimeout to stop the timer and prevent the function from being executed.

How to create a delay using setTimeout in jQuery?

While jQuery has its own delay method, you can still use setTimeout in the jQuery context. You will use it like you would in plain JavaScript by passing functions and delays to setTimeout.

What is the difference between

setTimeout and jQuery's delay method?

While both the setTimeout and jQuery's delay methods can be used to create delays, they work slightly differently. setTimeout is used for JavaScript functions, while delay is used for jQuery animation. delay Specifically designed for use with jQuery's effect queues.

Can I use async/await in setTimeout?

Yes, you can create delays in an asynchronous function using async/await and setTimeout. To do this, you need to wrap the setTimeout in a promise.

Why does my setTimeout not work?

Your setTimeout may not work for several reasons. You may have made a syntax error, or you may be trying to use a variable that has not been defined yet. The delay may also be too short to notice, or the function you are trying to execute may cause an error.

Can I use setTimeout in a loop?

Yes, you can use setTimeout in a loop. However, since setTimeout is non-blocking, all timeouts will be started simultaneously. If you want to create a series of delays, you need to add delays for each iteration of the loop.

How to test a function using setTimeout?

Testing functions using setTimeout can be tricky because of the delay. One way is to use a test framework that supports asynchronous testing. Another way is to simulate setTimeout so that you can control the execution time of the function.

Is there a limit to the delay that I can set using setTimeout?

The maximum delay you can set using setTimeout is 2147483647 milliseconds, about 24.8 days. If you try to set a longer delay than this, it will be reduced to 1.

The code has been modified, and loading prompts and completion status prompts have been added to make it clearer and easier to understand. The image path remains the same.

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