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Using AJAX helpers

From: jQuery Essential Training

Video: Using AJAX helpers

In addition to the basic AJAX function, jQuery provides a set of shorthand helper methods that help cover some common scenarios that arise when using AJAX with jQuery, and we're going to take a look at a couple of those now. So here in the jQuery API documentation, I'm going to click in the AJAX section on the Shorthand Methods. You can see there is a small set of these. The get function loads data from the server using an HTTP get request, and that's sort of like using the AJAX function with the type property of get, only this is a shorter more convenient way of doing that.

Using AJAX helpers

In addition to the basic AJAX function, jQuery provides a set of shorthand helper methods that help cover some common scenarios that arise when using AJAX with jQuery, and we're going to take a look at a couple of those now. So here in the jQuery API documentation, I'm going to click in the AJAX section on the Shorthand Methods. You can see there is a small set of these. The get function loads data from the server using an HTTP get request, and that's sort of like using the AJAX function with the type property of get, only this is a shorter more convenient way of doing that.

The get function has a couple of specialized counterparts. There is getJSON for getting JSON data from the server, and then there is the getScript version, which loads a JavaScript file and then executes it. There is the post function, which is again, kind of like using the basic AJAX function, with a post option, but this is a more shorthand way of doing it. Then there is the load function, which loads data from the server and takes the content that comes back and puts it into the matched element. And so we are going to take a look at using the get function and the load function in this movie.

So let's take a look at the get function. The get function takes a URL and it takes any data that you want to send to the server--so these could be you know URL- encoded properties that would normally be sent on the query string. And then there's a function to call and case things are successful, and then there is an optional dataType. Now if you don't provide a dataType, the jQuery library will just simply try to make an intelligent guess as to what kind of data you're looking to come back, either XML JSON, text, whatever. This is a pretty simple function to use.

Let's go back over to our code and take a look at an example of using it. So here in Aptana Studio, I've got my Helpers_start document open, and it looks pretty similar to the one that we used in the previous movie for the AJAX function. Here, on my document ready function, I have a function called getData, and getData is what we're going to fill out. Now, last time when we did this-- remember we did $.ajax and that's not we're going to be doing this time. This time we are going to be using the get function.

And to do that I am simply going to write $.get, or of course I could have written you know jQuery.get, but dollar sign is more convenient. So I write $.get, and I am going to get the same text file, so it's going to be testdata.txt. And then I need to give the name of the success function and that's this function right here, successFn. When successFn is called, the result will be the data that came back from the server, and then we're going to get a reference to our content paragraph, which is right here and put the result inside of it.

Okay, so we're going to save this, and then once again, using Aptana Studio, I am going to run this using my local web server. And you can do this however you want to. You can post this to whatever server you use it for testing or whatever IDE you happen to be using. But I am going to run this using my local server here in Aptana, so I'll bring it up in Chrome, and you can see that what's happening is the result is coming back from the server and being placed into the paragraph. All right, so let's go back to the code. Now, it turns out that this combination right here of getting data and then using the successFn to put the result into an element on the page is so common that jQuery actually gives you a shorthand way just of doing that, and so let's go back up here to get data and comment this out.

What we're going to do this time is simply, on the element itself, dollar sign and we're going to get the content paragraph, we're going to call the load function. And the load function will actually go out and kick off an AJAX request, and we're going to ask for testdata.txt. Now, that's all that we need to do. So this right here, load, is going to go out to the server, look for this URL, take the result, and put it into whatever element matches this selector right here.

So we are going to save, and just to be sure that we're not somehow triggering the successFn, let's go ahead and comment that out. So we'll save and we'll run this again using the internal server, and you can see that it worked. So we refresh, and you can see that the text data is coming back from the server and being put into the element on the page all with one line of code. So if you have a need to use AJAX that fits one of these comment scenarios then the jQuery AJAX helper functions can make your job a lot easier.

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This video is part of

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jQuery Essential Training

49 video lessons · 95602 viewers

Joe Marini
Author

 
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  1. 2m 52s
    1. Welcome
      1m 9s
    2. Using the exercise files
      1m 43s
  2. 17m 37s
    1. What is jQuery?
      5m 19s
    2. Downloading and installing jQuery
      2m 20s
    3. Creating a simple jQuery-enabled page
      7m 12s
    4. Overview of features in jQuery
      2m 46s
  3. 59m 57s
    1. Overview of selectors and filters
      2m 9s
    2. Using basic jQuery selectors
      9m 6s
    3. Using basic jQuery filters
      8m 35s
    4. Using jQuery attribute filters
      6m 7s
    5. Child, visibility, and content filters
      9m 59s
    6. Form selectors and filters
      9m 3s
    7. Traversing documents
      9m 1s
    8. Understanding jQuery statement chaining
      1m 42s
    9. Practical example 1: Annotating page links
      4m 15s
  4. 47m 16s
    1. Creating, getting, and setting content
      5m 53s
    2. Manipulating attributes
      5m 43s
    3. Inserting content
      4m 57s
    4. Wrapping, replacing, and removing content
      5m 27s
    5. Working with CSS
      6m 19s
    6. Associating data with page elements
      9m 30s
    7. Practical example 2: Automatic TOC generator
      9m 27s
  5. 33m 6s
    1. Understanding the jQuery event handling features
      2m 4s
    2. Binding and unbinding events
      6m 23s
    3. Convenient event helper methods
      4m 40s
    4. Using the jQuery event object
      6m 21s
    5. Using miscellaneous event features
      4m 38s
    6. Practical example 3: Table striping and highlighting
      9m 0s
  6. 28m 45s
    1. Hiding and showing elements
      5m 23s
    2. Fading elements in and out
      4m 2s
    3. Sliding elements
      4m 3s
    4. Creating custom animations
      5m 58s
    5. Practical example 4: Image rotator
      9m 19s
  7. 25m 30s
    1. Introduction to jQuery UI
      3m 40s
    2. Exploring the jQuery UI widgets
      5m 24s
    3. Exploring the jQuery UI effects
      3m 58s
    4. Using the jQuery UI ThemeRoller
      4m 11s
    5. Downloading and installing jQuery UI
      8m 17s
  8. 47m 49s
    1. Overview of the sample web site
      3m 50s
    2. Using the accordion widget
      9m 14s
    3. Creating an image rotator
      10m 22s
    4. Building hover tooltips
      7m 26s
    5. Making an image selector
      9m 30s
    6. Using the Resizable effect
      7m 27s
  9. 30m 2s
    1. Working with Asynchronous JavaScript and XML (AJAX)
      10m 8s
    2. Using AJAX helpers
      4m 34s
    3. Understanding AJAX data types
      10m 14s
    4. Using global AJAX event handlers
      5m 6s
  10. 20s
    1. Goodbye
      20s

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