Never use alert() for debugging

One thing I learned today is to never use alert() for debugging pruposes. When the javascript alert() function is called it blocks every other action until the OK button is pressed. It means that your javascript code that is immediatly after the alert() call is delayed until you press OK.

It also means that the thread your browser gave to the javascript engine is halted during all this time.

Imagine you are binding keyboard shortcuts on your website to specific actions. Like pressing Ctrl+S will submit the current form. Of course, Ctrl+S is already defined as a shortcut in the browser, so you will take care of preventing the default behavior in your custom function (using return false, e.preventDefault(), e.stopPropagation() or any method defined in your framework to do that)

The problem is that is you call alert() in your function, the Javascript thread will be halted before you can make the call to stop the propagation and thus, the browser will take control again and firing its default shortcut.

So my advice is that you should never use alert for debugging. Use the console.debug() method shipped in firebur or directly write to the DOM but do not use alert().

Tags : #keyboard #javascript #browser #alert

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