How to solve jquery rendering accumulation

In web development, jQuery is one of the most commonly used JavaScript libraries. It is committed to making JavaScript code more concise, easy to use and maintainable. Using jQuery, you can easily handle tasks such as DOM operations, event binding, animation effects, and Ajax data interaction. However, in actual development, we sometimes encounter the need to dynamically generate, render data, and implement accumulation in the page. This article will focus on how to use jQuery to solve the rendering accumulation problem.

Problem Description

Suppose we have a list that needs to be displayed dynamically, in which each item will have a number, and this number needs to be continuously accumulated. If we simply use JavaScript to implement it, we will encounter a disadvantage: every time the data is updated, the entire list needs to be re-rendered, making the visual effect of the page not smooth enough and the user experience poor.

The sample code is as follows:

<ul id="list">
    <li>1</li>
    <li>2</li>
    <li>3</li>
</ul>

let data = [1, 2, 3];

function render() {
  let list = $('#list');
  list.empty();

  for (let i = 0; i < data.length; i++) {
    let num = data[i];
    let li = $('<li></li>');
    li.text(num);
    list.append(li);
  }
}

function update() {
  for (let i = 0; i < data.length; i++) {
    data[i]++;
  }
  render();
}

setInterval(update, 1000);

In this sample code, we define a list datadata, where each element represents the number that needs to be displayed. The render() function will generate the corresponding HTML code based on the data data and insert it into the page. update()The function updates the data at certain intervals and re-renders the entire list. Although this code is simple to implement, each update requires re-rendering the entire list, which will cause a large performance loss.

Solution

In order to solve the above problem, we need to find a way to efficiently render new HTML code and insert it into the page after each data update without affecting other parts. There are two commonly used methods in jQuery:

Method 1: Modify DOM elements

The basic idea of ​​this method is to record the position corresponding to each number on the DOM element and index it Updates are made without re-rendering the entire list.

The sample code is as follows:

<ul id="list">
    <li data-index="0">1</li>
    <li data-index="1">2</li>
    <li data-index="2">3</li>
</ul>

let data = [1, 2, 3];

function render() {
  for (let i = 0; i < data.length; i++) {
    let num = data[i];
    let li = $('#list li[data-index="' + i + '"]');
    li.text(num);
  }
}

function update() {
  for (let i = 0; i < data.length; i++) {
    data[i]++;
  }
  render();
}

setInterval(update, 1000);

In this sample code, we added a data-index attribute to each li element, using Record the position corresponding to that number. In the render() function, we find the corresponding element based on the data-index attribute and update its displayed number.

Method 2: Using text nodes

The basic idea of ​​this method is to use text nodes to directly update numbers and insert them into DOM elements, which is more efficient than directly operating DOM elements.

The sample code is as follows:

<ul id="list">
    <li></li>
    <li></li>
    <li></li>
</ul>

let data = [1, 2, 3];

function render() {
  let list = $('#list');
  list.empty();

  for (let i = 0; i < data.length; i++) {
    let numNode = document.createTextNode(data[i]);
    let li = $('<li></li>');
    li.append(numNode);
    list.append(li);
  }
}

function update() {
  for (let i = 0; i < data.length; i++) {
    data[i]++;
  }
  render();
}

setInterval(update, 1000);

In this sample code, we first create an empty li element and use document.createTextNode()Method creates a text node. Then, we use jQuery's append() method to insert the text node into the li element, and finally insert the li element into the page.

Summary

In this article, we introduced two ways to use jQuery to solve the rendering accumulation problem. Using these methods, you can avoid the efficiency problem of re-rendering the entire list every time the data is updated, and improve the page's response speed and user experience. Of course, in specific development, we need to choose the most appropriate method for implementation based on the actual situation.

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