jquery macro replacement function

jQuery Macro Replacement Function: How to simplify code and improve efficiency?

In front-end development, we often need to operate DOM, styles, events, etc., and different pages may have multiple similar elements that need to be processed. In this case, similar code needs to be written, which is not only a waste of time, but And it is not easy to maintain. To address this problem, jQuery provides a macro replacement function, which allows us to simplify the code and improve efficiency.

1. What is the macro replacement function?

The Macro Replacement function (Macro Replacement) is an excellent function assistant in jQuery. It allows us to easily save some code blocks and then replace them at the specified location when needed. This not only preserves the reusability of the code, but also makes our code more readable and understandable.

2. How to use macros to replace functions?

jQuery’s macro replacement function mainly includes two methods: $.macro and $.processTemplate. Among them, $.macro is used to define the template, and $.processTemplate is used to process the template. The basic syntax of

$.macro:

$.macro(name, string)

Among them, name represents the name of the template, and string represents the content of the template (can be any Strings, including HTML tags, JavaScript codes, etc.).

For example, we define a template named "myTemplate", the content is a piece of HTML code:

$.macro("myTemplate", "<div class='item'><h2 id="title">{title}</h2><p>{description}</p></div>");

Among them, {title} and {description} are placeholders, indicating the need The content to replace.

Next, we can use the $.processTemplate method to process the template and replace the placeholder:

var data = {title: "这是一个标题", description: "这是一些描述信息"};

var html = $.processTemplate("{myTemplate}", data);

$("#content").append(html);

Note: The template name here must be included in a pair of curly brackets, such as " {myTemplate}".

After executing the above code, a piece of HTML code will be added to the #content element with the following content:

<div class="item">
    <h2 id="这是一个标题">这是一个标题</h2>
    <p>这是一些描述信息</p>
</div>

3. Advanced application of macro replacement function

1. Support Nested template

The macro replacement function also supports nested templates, which can nest another template within one template, similar to the combination mode. The implementation is similar to ordinary templates, just use nested curly braces in the template.

For example, we define a large template consisting of two templates, one template is used to display the title and content of a news, and the other template is used to display comments:

$.macro("item", "<div class='item'><h2 id="title">{title}</h2><p>{content}</p>{comments}</div>");

$.macro("comment", "<div class='comment'>{content}</div>");

Note, {comments} here is a placeholder for nested comment templates.

Next, we use simulated data to generate a set of news:

var news = [
    {title: "标题1", content: "内容1", comments: [
        {content: "评论1.1"},
        {content: "评论1.2"}
    ]},
    {title: "标题2", content: "内容2", comments: [
        {content: "评论2.1"},
        {content: "评论2.2"}
    ]}
];

Finally, we loop through the news and use the $.processTemplate method to generate HTML code according to the defined template and insert it into In the page:

for (var i = 0; i < news.length; i++) {
    var newsItem = news[i];
    var html = $.processTemplate("{item}", newsItem, function (key, value) {
        if (key == "comments") {
            var commentHtml = "";
            for (var j = 0; j < value.length; j++) {
                var comment = value[j];
                commentHtml += $.processTemplate("{comment}", comment);
            }
            return commentHtml;
        }
        return value;
    });
    $("#news").append(html);
}

Note that the third parameter here is a callback function, which is used to process the {comments} placeholder in the nested template and replace it with the HTML code generated by the comment template.

After executing the above code, the following HTML code will be generated in the #news element:

<div class="item">
    <h2 id="标题">标题1</h2>
    <p>内容1</p>
    <div class="comment">评论1.1</div>
    <div class="comment">评论1.2</div>
</div>
<div class="item">
    <h2 id="标题">标题2</h2>
    <p>内容2</p>
    <div class="comment">评论2.1</div>
    <div class="comment">评论2.2</div>
</div>

2. Supports looping

The macro replacement function also supports the generation of complex HTML code, such as a list containing a loop. This can be achieved by using the {loop} placeholder in the template.

For example, we define a template named "list" to generate a list containing a loop:

$.macro("list", "<ul>{loop}</ul>");

Then, we can define a template named "item", using To generate an item in the list:

$.macro("item", "<li>{text}</li>");

Next, we define an array containing the list item data to be generated:

var data = [
    { text: "列表项1" },
    { text: "列表项2" },
    { text: "列表项3" }
];

Finally, we can write a loop according to the following code to generate a list:

var html = $.processTemplate("{list}", data, function (key, value) {
        if (key == "loop") {
            var loopHtml = "";
            for (var i = 0; i < value.length; i++) {
                loopHtml += $.processTemplate("{item}", value[i]);
            }
            return loopHtml;
        }
        return value;
    });

$("#content").append(html);

The callback function here is similar to the previous example and is used to process the {loop} placeholder, iterate through the array and generate multiple list item HTML codes.

After executing the above code, a piece of HTML code will be added to the #content element, the content is as follows:

<ul>
    <li>列表项1</li>
    <li>列表项2</li>
    <li>列表项3</li>
</ul>

4. Summary

The macro replacement function is very practical in jQuery Function, it allows us to easily handle DOM, styles, events, etc., avoid duplication of code, and improve development efficiency. Through the introduction and example demonstration of this article, I believe that readers have a deeper understanding of the macro replacement function and can use it flexibly in actual development. Of course, there are more advanced applications of macro replacement functions, and readers are welcome to continue to study and research in depth.

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