Jquery why return false

What are source maps in jQuery? What does the jQuery migrate function do? Differences Between jQuery. How can you delay document. How to disable cut,copy and paste in TextBox using jQuery? How to prevent Right Click option using jquery? How does the jQuery pushStack function work? Why use jQuery filter Methods?

Difference between find and closest in jquery? Can we call C code behind using jQuery? How to include jQuery in ASP. Or you can construct your handler to take event as a parameter better for testing So you can already see the difference.

With addEventListener we aren't wrapped in an onclick function. Our handler receives the event parameter directly and so we can call it whatever we want. Also our return false is at the "top level" here and we don't have to worry about adding an extra return statement like with onclick. So it looks like it should work. Clicking on the link we get the alert. So with addEventListener use event. The event handler processing algorithm for an event handler H and an Event object E is as follows:.

So it seems to imply that return false cancels the event for both addEventListener and onclick. An event handler has a name, which always starts with "on" and is followed by the name of the event for which it is intended. The first way, common to all event handlers , is as an event handler IDL attribute.

The second way is as an event handler content attribute. Event handlers on HTML elements and some of the event handlers on Window objects are exposed in this way. Python Javascript Linux Cheat sheet Contact.

Event registration interfaces states that handleEvent in the EventListener has no return value: handleEvent This method is called whenever an event occurs of the type for which the EventListener interface was registered. The preventDefault function simply stops the default HTML behavior from occurring, so the link click won't take the user anywhere, it will simply run the jQuery code from within the function. When you return false, jQuery automatically runs both the stopPropagation and preventDefault functions.

Feed dashboard icon Created with Sketch. Before, when you were mis using return false , it always had to go at the end of your function, or at least at the end of a particular line of logic where no further execution was needed. With e. It can be called at any time during a callback function to take effect. So where should you put it?

During development, it should almost always be the very first line. The last thing you want is for your form you are trying to AJAXify to actually submit to another page while you try to debug a JavaScript error in the callback. In production, if you are following progressive enhancement, put it at the bottom of the callback, or at the end of execution flow.

The benefit here, however, is not related to browsers with JS turned off, but rather browsers with it turned on in the situation where your code throws an error! Take a look at the following code:. The same applies for form submit events as well, provided you have the proper fallback information in place. Never count on your code always working.

It is far better to plan for a nice fallback than assume errors will never occur! In production, if the functionality is JavaScript only, keep the call on the first line.

The concept here is this: If this part of your functionality was added with JavaScript in the first place, then a fallback is not really as necessary.