Javascript Running Code Once

I only want my JavaScript to run once, but I cannot control how many times the javascript file is executed. Basically I'm writing a tiny JS snippet into a CMS, and the CMS is actua

Solution 1:

Try this:

var doneTheStuff;
function whatever() {
  if (!doneTheStuff) {
    doneTheStuff = true;
    // do the stuff
  }
}

Redundant variable declarations don't affect the value of the variable. Once one of the functions has set the variable to true, the others won't do anything.

Solution 2:

if (typeof code_happened === 'undefined') {
  window.code_happened = true;
  // Your code here.
}

The typeof check gets you around the fact that the global hasn't been declared. You could also just do if (!window.code_happened) since property access isn't banned for undefined properties.

Solution 3:

Use a closure, and set a flag. If the flag is true, just return:

if ( ! window.never_called_again  ) {
    window.never_called_again = (function () {
        var ran = false;
        returnfunction (args) {
            if ( ran ) return;
            ran = true;
            // Do stuff
        };
    }());
}

Here's the fiddle: http://jsfiddle.net/U2NCs/

Solution 4:

With jQuery, the function .one() may be useful : http://api.jquery.com/one/

W3School exemple here : http://www.w3schools.com/jquery/event_one.asp