Is there a best practice for generating html with javascript

ckarbass_67719 0
Viewed 97893

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.
dynamic dhtml html ajax javascript
8 Answers

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.

Jim_Fiorato_6500

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.

some_368660

Either of the first two options is both common and acceptable.

I'll give examples of each one in Prototype.

// assuming JSON looks like this:
// { 'src': 'foo/bar.jpg', 'name': 'Lorem ipsum' }

Approach #1:

var html = "<div><img src='#{src}' /> #{name}</div>".interpolate(json);
$('container').insert(html); // inserts at bottom

Approach #2:

var div = new Element('div');
div.insert( new Element('img', { src: json.src }) );
div.insert(" " + json.name);
$('container').insert(div); // inserts at bottom
savetheclocktower_257200

Here's an example, using my Simple Templates plug-in for jQuery:

var tmpl = '<div class="#{classname}">#{content}</div>';
var vals = {
    classname : 'my-class',
    content   : 'This is my content.'
};
var html = $.tmpl(tmpl, vals);
Andrew_Hedges_115770

You could add the template HTML to your page in a hidden div and then use cloneNode and your favorite library's querying facilities to populate it

/* CSS */
.template {display:none;}

<!--HTML-->
<div class="template">
  <div class="container">
    <h1></h1>
    <img src="" alt="" />
  </div>
</div>

/*Javascript (using Prototype)*/
var copy = $$(".template .container")[0].cloneNode(true);
myElement.appendChild(copy);
$(copy).select("h1").each(function(e) {/*do stuff to h1*/})
$(copy).select("img").each(function(e) {/*do stuff to img*/})
Leo_206890
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