如何检查文档是否已准备好在JavaScript中？

Question

I am developing a simulator to simulate user actions in a Web page. In a special case, there are a few number of buttons in a page clicking on each changes the content of the page. I programmatically click on each button and then want to extract the new content added to the page. If you have a look at:

http://www.elementbars.com/Build-a-Bar-Service.aspx#

you can find an example.

My code is something like this:

---

for (var int i=0; i< buttonArray.length; i++){ // buttonArray is the array of buttons
    triggerClickEvent(buttonArray[i]);
    extractNewContent();
}

function triggerClickEvent (clickableElement) {
   jQuery(clickableElement).trigger('click');
}

---

Both triggerClickEvent and extractNewContent are properly working, but the problem is that after triggering the click event, the JavaScript engine should wait for a while to make sure that the new content is added, but it does not behave as expected. For example, I noticed that all the buttons are clicked, but extractNewContent extracts content for the first button, meaning the these two functions are not working synchronously. I used the setTimeout function, but since it does not block the execution, so could not resolve the problem. I also used functions checking the state of the document, but not working as well.

I would be grateful if you could please help me.

Thanks.

Answer 1

The easiest way to do it is with a toolkit like jQuery. Something like this:

jQuery(document).ready(function() {
...
});

or the more concise

jQuery(function() {

});

Part of the problem is that "ready" is not standardized across browsers. Toolkits like jQuery make up for that.

Answer 2

You can pass parameters to trigger function one of them would be a callBack function extractNewContent in our case. And call this function after all modifications are done in click event handler. So the handler would be

$(clickableElement).on('click', function(event, callback){
                       ...
                       all DOM modifications goes here
                       ...
                       if(typeof callback === "function")
                           callback();
                       }

and then trigger it with extractNewContent as parameter

$(clickableElement).trigger('click',extractNewContent);

Answer 3

The following code works:

for (var int i=0; i< buttonArray.length; i++){ // buttonArray is the array of buttons
  triggerClickEvent(buttonArray[i]);
  alert('balalalala'); // if you remove this, it won't work.
  extractNewContent();
}

function triggerClickEvent (clickableElement) {
 jQuery(clickableElement).trigger('click');
}