Is there a best practice for generating html with javascript

Question

I'm calling a web service that returns an array of objects in JSON. I want to take those objects and populate a div with HTML. Let's say each object contains a url and a name.

If I wanted to generate the following HTML for each object:

<div><img src="the url" />the name</div> 

Is there a best practice for this? I can see a few ways of doing it:

1. Concatenate strings
2. Create elements
3. Use a templating plugin
4. Generate the html on the server, then serve up via JSON.

Answer 1

Options #1 and #2 are going to be your most immediate straight forward options, however, for both options, you're going to feel the performance and maintenance impact by either building strings or creating DOM objects.

Templating isn't all that immature, and you're seeing it popup in most of the major Javascript frameworks.

Here's an example in JQuery Template Plugin that will save you the performance hit, and is really, really straightforward:

var t = $.template('<div><img src="${url}" />${name}</div>');  $(selector).append( t , {      url: jsonObj.url,      name: jsonObj.name }); 

I say go the cool route (and better performing, more maintainable), and use templating.

Answer 2

If you absolutely have to concatenate strings, instead of the normal :

var s=""; for (var i=0; i < 200; ++i) {s += "testing"; } 

use a temporary array:

var s=[]; for (var i=0; i < 200; ++i) { s.push("testing"); } s = s.join(""); 

Using arrays is much faster, especially in IE. I did some testing with strings a while ago with IE7, Opera and FF. Opera took only 0.4s to perform the test, but IE7 hadn't finished after 20 MINUTES !!!! ( No, I am not kidding. ) With array IE was very fast.