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javascriptboolean-operations

Javascript approaches to boolean reversal

The following applies to any boolean variable, but I was writing a little function in javascript which reverses the check in a given checkbox, became bored, and wondered how much I could condense it.

Started with:

checkbox = document.getElementById('checkbox');
checkbox.checked = (checkbox.checked ? false : true);

Then moved to

checkbox = document.getElementById('checkbox');
checkbox.checked = !(checkbox.checked);

And then

document.getElementById('checkbox').checked ^= 1;

I couldn't figure out a logical unary approach, like

!(document.getElementById('checkbox').checked);

But I found that -- works, though ++ doesn't (abs val?)

document.getElementById('checkbox').checked--;

I'm also not sure if js (or any language, for that matter) supports some implicit reference to the variable on the left side of the equation, as in:

document.getElementById('checkbox').checked = !(left.side);

There are usually 1000 ways of doing the same thing.. any other neat approaches? Is there a "best" approach for any reason (or most compatible from language to language)?

Solution

  • I always use something like this.checked = !this.checked for it's the most logical and readable solution I know of. Plus it works in any language I use.