jquery global settings

jQuery is one of the most popular JavaScript libraries in modern web development. It provides developers with a reliable and easy-to-use way to manipulate HTML documents, handle events, create animations, perform Ajax interactions and many other common tasks. . However, when developing a large website or application, you may need to use jQuery in multiple pages, and you may need to run it in different configurations. To this end, jQuery provides some global settings options so that developers can share their configurations across multiple pages. Here are some common jQuery global settings options.

1. $.ajaxSetup()

The $.ajaxSetup() method allows you to set global AJAX options for jQuery. These options will apply to all $.ajax(), $.get(), $.post(), etc. AJAX requests you write in different pages or different sections. This is a global setting option that will affect all your requests.

You can use the $.ajaxSetup() method in the following ways:

$.ajaxSetup({
  url: "/api/user",
  type: "POST",
  dataType: "json"
});

In the above example, we set the default URL, HTTP method and response data type for AJAX requests. These settings will apply to all AJAX requests called across the site.

2. $.ajaxPrefilter()

$.ajaxPrefilter() method allows you to preprocess the request data before the AJAX request is sent. It is similar to $.ajaxSetup(), but it only affects the AJAX request when it is called. By using $.ajaxPrefilter(), you can modify request parameters and response data, or run validation logic before the request is sent.

The following is an example of using $.ajaxPrefilter():

$.ajaxPrefilter(function(options, originalOptions, jqXHR) {
  options.url = "/api" + options.url;
});

In the above example, we have added the prefix "/api" in front of the URL for all AJAX requests. Doing this avoids entering this prefix repeatedly in AJAX requests.

3. $.ajaxTransport()

The $.ajaxTransport() method allows you to register a new AJAX transport. By default, jQuery supports XMLHttpRequest and script tag transports, but you can register a custom transport via $.ajaxTransport().

The following is an example of using $.ajaxTransport():

$.ajaxTransport("+image", function(options, originalOptions, jqXHR) {
  var img,
      deferred = $.Deferred(),
      dataType = options.dataType || "";

  if (dataType.toLowerCase() === "image") {
    img = new Image();

    img.onload = function() {
      deferred.resolve(this);
    };

    img.onerror = function() {
      deferred.reject();
    };

    img.src = options.url;

    return deferred.promise();
  }
});

In the above example, we registered a new data type "image" and defined how to pass the Image object Make the transfer. This saves time and bandwidth in loading and displaying images in AJAX requests.

4. $.holdReady()

$.holdReady() method allows you to pause or resume jQuery's ready event. The ready event is the $(document).ready() event, which will be triggered when the DOM is fully loaded and parsed. By using $.holdReady() you can delay or prevent the firing of the ready event to wait for certain conditions before other code runs.

The following is an example of using $.holdReady():

$.holdReady(true);

$.get("/settings", function(data) {
  // Some data processing here
  $.holdReady(false);
});

In the above example, we pause jQuery's ready event before getting the settings information. After $.get() completes and the data is processed, we release $.holdReady(), allowing the ready event to fire again.

Summary

jQuery provides some useful global setting options that can help web developers handle many common web tasks in a reliable and consistent way. Through methods such as $.ajaxSetup(), $.ajaxPrefilter(), $.ajaxTransport() and $.holdReady(), developers can share their configurations between multiple pages, preprocess AJAX requests, and register custom AJAX Transport and control jQuery's ready events. These options increase productivity, improve website performance, and make implementing complex web applications more efficient.

The above is the detailed content of jquery global settings. For more information, please follow other related articles on the PHP Chinese website!