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How to pass boolean values between PHP, HTML forms, and Javascript

rated 0 times [ 33] [ 7] / answers: 1 / hits: 20643 / 7 Years ago, tue, april 18, 2017, 12:00:00

I have a PHP program that uses HTML forms and uses JavaScript for validation. There's a hidden field in the HTML form containing a boolean value that gets set by PHP, validated on submission by JavaScript, and passed to another PHP page.

When I tried to use PHP booleans to set the value of the HTML field, JavaScript evaluated it as blank, so I used ones and zeros and compared them numerically instead, and now it works fine.

My question is: what is best practice in this scenario? How do I get JavaScript to read a true/false value in my PHP-driven HTML hidden field without using ones and zeros? Or is that just a bad idea altogether?

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answered 7 Years ago karleel · Accepted Answer

The good news is that PHP and JavaScript have a similar idea about what values are true and false.

An empty string will be false on both sides. A string with something in it (except 0 in PHP) will be true on both sides.

The number 0 will be false on both sides. All other numbers will be true on both sides.

Since the values of a form will always be strings, as Quentin pointed out in his answer, a good practice might be to use an empty string as false value and something else (e.g. 'true') as true value. But I think your way of using 0 and 1 and testing the numerical values is the safest approach because it isn't misleading. (When someone sees 'true' they might think 'false' would also be usable for a false value.