CODEWITHSUNDEEP
phphtmllocal-storage
Heigo
Heigo

Reputation: 946

use html localStorage in PHP

My main question is, why the below code prints out:

false

boolean value true

I would expect the variable "boolean" value is also false

I want to store some data in javascript and later use it in PHP, is it even possible?

<!doctype html>
<html lang="en">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>Storage test?</title>
</head>
<body>
    <script type='text/javascript'>
        localStorage.save = 'false';
    </script>
    <?php
        $boolean = "<script type='text/javascript'>" .
                   "document.write(localStorage.save);".
                   "</script>";

        echo $boolean;

        if($boolean = 'true'){
            echo "<p>boolean value true</p>";   
        } else {
            echo "<p>boolean value false</p>";  
        }
    ?>

</body>

Upvotes: 0

Views: 9580

Answers (5)

Phoebe
Phoebe

Reputation: 108

Using = will only assign $boolean with that value and will return true because it's not false, 0, or null. Try using == or ===. :)

Upvotes: 0

MrBoolean
MrBoolean

Reputation: 601

One = is to assign, comparison is either == or ===.

This example displays "Hello":

<?php
function getData()
{
    return 'Hello';
}

if ($data = getData()) {
    echo $data;
}

This example displays "23":

<?php
function getData()
{
    return 'Hello';
}

$data = getData()

if ($data === 'hello') {
    echo 1;
}

if ($data == 'hello') {
    echo 2;
}

if ($data === 'Hello') {
    echo 3;
}

Upvotes: 0

w00
w00

Reputation: 26792

Like said, you're not comparing, but assigning because of the single equal sing = in the if statement.

Next to that you cannot directly read the localStorage from PHP. So even if you had a double equals == to compare, then it would still outout boolean value true.

That is because you put a string inside $Boolean:

$boolean = "<script type='text/javascript'>document.write(localStorage.save);</script?";

You're not evaluating any JavaScript code like that.

When a PHP variable contains something, wether it be a string or number etc. it will always evaluate to true inside an if statement. Unless the value is either false, 0 or null.

To compare a real Boolean value you have to use an explicit compare. You do that with three equal signs ===.

if ( $someBool === true )
{ // do stuff }

But no, you cannot directly get the localStorage value from JS to PHP. You'd need an Ajax call to pass it back to PHP. And I think that is what you're ultimately trying to do.

Upvotes: 4

Kadmillos
Kadmillos

Reputation: 74

I guess it's a typo in the if you make

if($boolean == 'true'){
    ....
}

Upvotes: 0

f2lollpll
f2lollpll

Reputation: 1007

if($boolean = 'true'){ <-- this line
        echo "<p>boolean value true</p>";   
    } else {
        echo "<p>boolean value false</p>";  
    }

You are not comparing the $boolean variable with 'true', but assigning the value 'true'.

Try two equal signs.

I'm not even sure what you're doing is possible. But the equal sign is definately a problem.

Upvotes: 4

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