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javascriptphp
morsch
morsch

Reputation: 11

String "true" from javascript not recognised in php as that string value

I call a javascript query within php function to test if user wants to allow certain action. The value returned from javascript is either string value 'true' of 'false'. If I test in php to see if string, returns true, if I test is as $var=='true' it returns false. Please help with my apparently daft oversight.

I have tested it to ensure it numerous ways to see what value is returned, string, boolean, 1,0 integer, but indicates string

    if (file_exists($target_file)) {
    function prompt($prompt_msg){
    echo("<script type='text/javascript'> var answer = confirm('".$prompt_msg."'); </script>");

    $answer = "<script type='text/javascript'> document.write(answer); </script>";
    return($answer);
    }
    //program

    $prompt_msg = "Overwrite curent file?";
    $name = prompt($prompt_msg);

    }

    //This returns 'true' or  'false' string value for php sake

    if (is_string($name))
    {echo "YES";} else 
    {echo "NO";}

    //This always returns YES if I select OK (true) or Cancel (false) in above javascript

    echo gettype($name);

    //This returns string

    echo $name;

    /*****/   if($name == 'true') {
    $uo = 1;
    echo 'success';
    } elseif($name == 'false') {
    $uo = 0;
    }
    else {;
    $uo = '??';
    }
    echo $uo;

***//If I replace this statement with if($name == true) whther the javascript returned string is true of false it always gives $uo = 1;

//Whether the javascript value is 'true' or 'false' is will always return ??

Php if query should assign 1 to $uo if 'true' else '0' if false

Upvotes: 1

Views: 559

Answers (3)

Kannan G
Kannan G

Reputation: 1004

Your conditions will get executed in PHP not in javascript.

When converting to boolean, the following values are considered FALSE:

the boolean FALSE itself
the integer 0 (zero)
the float 0.0 (zero)
the empty string, and the string "0"
an array with zero elements
an object with zero member variables (PHP 4 only)
the special type NULL (including unset variables)
SimpleXML objects created from empty tags

Refer -

The if statement doesn't work for false in php

Check if boolean is true or false

Also note

var_dump(0==FALSE);    //bool(true)  
var_dump(0===FALSE);   //bool(false)

Upvotes: 0

user8977154
user8977154

Reputation: 403

PHP is server side and the JavaScript is client side (not considering NodeJS).

That said when you call the page the PHP is run completely without waiting for the JavaScript you made, actually PHP only builds the webpage that contains the script and only when the browser receives this page that it will execute the JavaScript, but PHP has already finished all its execution.

In your example code what $answer contains is the string <script type='text/javascript'> document.write(answer); </script> and not the result of the execution of the JavaScript, because PHP can't execute a script like that.

If this PHP is to be executed on a browser context you need to change the JavaScript to recall the PHP url passing the value of the confirm dialogue in a query, and the PHP to check the passed query with something like parse_str($_SERVER['QUERY_STRING'], $query); and only build the page when none is passed and to continue execution if it receives a true.

@v-prince answer gives you the idea of how to do the client side.

Upvotes: 0

V. Prince
V. Prince

Reputation: 130

I hope this will give you some idea.. Good Luck

sample.html

<input type='button' class='test'>

<!-- make sure you have a jquery plugin and check the path of your jquery -->
<script src="jquery.js"></script>

<script>

$(document).ready(function(){
  $('.test').click(function(){
   var answer = confirm('are you sure you want to click me?');
   $.ajax({
    url : 'yourPHP.php',
    type : 'post',
    data : { answerValue : answer },
    success : function( result ){
     // do something
    }
  });
 });
});

</script>

Upvotes: 0

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