0

I have a webpage which incorporates a query/ajax function so that when a text box is completed, a php file is run which autofills some other inputs in the form.

In the php file I run, initally I was using return to send the appropriate data to the jquery/ajax function. However, this wasn't working. I have since found it only works with echo.

Having read about return and echo, I think it is something to do with query/javascript being a client-side language and therefore the request is coming from the browser which requires echo rather than return.

Is this the case - can anyone explain more helpfully why return wont work, and when I should use each.

Ben Thompson
  • 4,743
  • 7
  • 35
  • 52

4 Answers4

2

return returns data to the caller. That's a mechanism entirely internal to PHP which does not produce any output.

Calling a PHP script via AJAX, you're making an HTTP request. The return value will be the HTTP response. You're never calling a "PHP function" via AJAX, you're making an HTTP request like for any other web site. Only output will be in the HTTP response. echo produces output, return doesn't.

Just look at the raw request and response by opening the URL directly in your browser, using the browser net inspection tools or by manually making the request with curl or so. There's no magic to it, it's all just HTTP.

deceze
  • 510,633
  • 85
  • 743
  • 889
1

Let's ignore JavaScript for the moment; it's not the problem.

PHP is a language centrally focused on generating text. It's so focused on generating text that it actually defaults in copying text from its input to its output; only when you chant the magic incantation <?php does it actually start doing real work.

Since it's so output-focused, you might expect that it has an easy way to send some text to its output, and you'd be right: it's called echo. echo outputs data.

Of course, most modern programming languages have functions. Functions can return values. Of course, it also makes sense that a function might want to output some data and return a value. return returns a value from a function.

icktoofay
  • 126,289
  • 21
  • 250
  • 231
0

Return only works with passing data between functions on the server side. Data sent to the browser, on the other hand, has to be echoed.

Expedito
  • 7,771
  • 5
  • 30
  • 43
0

return is used to return a value from a function to the calling code. It passes values about within your PHP script.

echo outputs its arguments to the output buffer which is in turn sent to the browser.