Question

If I want to add an isEmpty method to all JavaScript arrays, I would use the following code

Array.prototype.isEmpty = function() {   return this.length == 0; } 

Assume this code is in a file foo.js. If I want isEmpty to be available on all pages of a web site, would I need to include foo.js in all the HTML files? In other words, do the prototypes get ‘reset’ whenever the user navigates to a different page?

Thanks, Don

Answer 1

Yes, you wil need to include your code on each page load.

Think of each page load as a compile/linking cycle. All the various bits of Javascript on the page are linked together¹ and then executed as one giant program. The next time a page is loaded, the default Javascript objects start in a fresh state.

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1. Linked together in a brain-dead ‘every piece of code shares the same global namespace’ fashion