Just wondering if this is okay to do? I have to store some PHP variable values into LocalStorage.

if($res->status == "success"){

            echo '<script>alert("alrighty sparky! lets get you in...");</script>';
            echo '<script>localStorage.setItem("token", JSON.stringify({"token": "'.$res->token.'" }))</script>';
            echo '<script>localStorage.setItem("username", JSON.stringify({"username": "'.$data->username.'" }))</script>';
            echo '<script>localStorage.setItem("id", JSON.stringify({"id": "'.$data->id.'" }))</script>';

            $boarding_url =  base_url() . 'index.php/boarding/teddies';

No, it doesn't work like that because you're not escaping your PHP strings to be a safe JavaScript string. What you're doing is encoding them as JSON but if - for example - $res->token contains \ then it will produce a broken JavaScript string and JSON.stringify() won't fix it.

Correct code must use json_encode() for this purpose.

echo '<script>localStorage.setItem("id", "'.json_encode($data->id).'")</script>';

Also note that you don't need to repeat <script> tag each time:

echo '<script type="text/javascript">';
// Write all lines here, don't forget semicolon at the end of each one
echo 'localStorage.setItem("id", "'.json_encode($data->id).'");';
echo '</script>';

As noted in the answer by Adriano Repetti, as you are outputing raw data into the javascript source, you could create invalid javascript. For example a quote in $res->token could create the following syntax error:

<script>localStorage.setItem("token", JSON.stringify({"token": "token with a " (quote)" }))</script>';

The SO highlighter makes this error quite obvious.

Aslo, as pointed out by Adriano, php's json_encode() takes care of this nicely.

However, whenever i find myself mixing js with a server side language, i endevour to keep the interleaving to an absolute minimum, to reduce confusion.

With that in mind, i would format the data in php, then output it a single place, creating an object that js can process:

if($res->status == "success"):
    $jsData = [
        'storageData' =>[
            'token'    => $res->token,
            'username' => $res->username,
            'id'       => $res->id
       'redirectUrl' => base_url() . 'index.php/boarding/teddies'

        var data = <?php echo json_encode($jsData);?>;
        for(var item in data.storageData){
            localStorage.setItem(item, storageData[item]);


(Unfortunately the SO syntax highlighter is not so clever here..)

With regards to the redirect:


Presumably this function is also outputting javascript (as a regular header redirect would be impossible at this point, as the response body has already been sent), so for clarity i included redirect in the above js block.

Additionaly, this looks like a bit of a code smell - returning a response to the browser just to set some js data then performing another request back to the server.

saving the data in session, redirecting directly to the final destination (index.php/boarding/teddies) and have that page retrieve its data from session would probably make more sense, but thats another question.

  • \$\begingroup\$ Much apprecitated! Thanks Steve. I had this session option under consideration but the infrastructure been developed so far is making me to follow localstorage instead of session. I will make changes in the infrastructure in future and change this localstorage into session. Thanks again! \$\endgroup\$ – Faisal Ashfaq Jan 21 '16 at 5:37
  • 1
    \$\begingroup\$ My upv, I like this, less mixing means less typos you will search for hours! \$\endgroup\$ – Adriano Repetti Jan 22 '16 at 8:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.