减少HTTP请求

I'm using this code to dynamically load external pages

$(function() {
   $('#nav a').click(function() {
    var page = $(this).attr('href');
    $('#content').load(page + '.php');
    return false;
    });
});

I've noticed that each time I click on one of the menu tabs, a new HTTP request is sent and the page is loaded again. I'm wondering how to make each page load once so when I go through the tabs, the pages that have been already loaded display without sending new requets ?

You could "tag" tabs that are already loaded with a flag using .data() and only issue the HTTP request when the tag is non-existent.

Edit: Regarding Kryptonite's comment this would be a simple approach to the problem:

var pages = {};

$(function() {
  $('#nav a').click(function() {
    var page = $(this).attr('href');

    if (!(page in pages)) {
      $.get(page, function (data) {
        pages[page] = data;
      });
    }

    $('#content').html(pages[page]);

    return false;
  });
});

$('#nav a').click(function(e) {
    e.preventDefault();
    $this = $(this);
    if ($this.data('loaded') !== true) {
        // Load it.
        $this.data('loaded', true);
    } else {
        alert('Already loaded that one!');
    }
});

This will do what you need. You'll need to throw your load code in where I have the // Load it. comment, and might want to remove the else block as well. http://jsfiddle.net/rRumK/