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POGoogle Chrome Extension Variable using sendMessage from Content Script to Background Page is Undefined
 

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  1. POGoogle Chrome Extension Variable using sendMessage from Content Script to Background Page is Undefined
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    <p>I have a basic Google Chrome Extension I am working on, and having a problem getting a value from localStorage. I am using sendMessage in the content script to ask for the variable from the background page. When I get the response, the variable is always "undefined", unless I put something like an alert() after the response...then the variable contains my value. Can you help me to figure out why this is and how to do it correctly? I have made the code for this post and it is below. Thank you very much!</p> <hr> <h2>manifest.json</h2> <pre><code>{ "name": "Test Extension", "version": "1.0", "manifest_version": 2, "description": "A test extension.", "background": { "scripts": ["background.js"] }, "content_scripts": [ { "matches": ["&lt;all_urls&gt;"], "js": ["content.js"] } ], "permissions": [ "tabs", "&lt;all_urls&gt;" ] } </code></pre> <hr> <h2>content.js</h2> <pre><code>alert('content'); var color; chrome.extension.sendMessage({greeting:"color"},function(response){color = response.farewell;}); // alert('pause'); // uncommenting this line lets me get the value...why? alert('content - ' + color); </code></pre> <hr> <h2>background.js</h2> <pre><code>alert('background'); localStorage["color"] = "lightblue"; var color = localStorage["color"]; alert('background - ' + color); chrome.extension.onMessage.addListener(function(request,sender,sendResponse) { if (request.greeting == "color") {sendResponse({farewell:color});} }); </code></pre> <hr> <p>Thank you very much for any help! :)</p>
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    1. COSee this answer to learn what's wrong with your code, and how to solve it: http://stackoverflow.com/a/11689804/938089
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      1. POGoogle Chrome Extension Variable using sendMessage from Content Script to Background Page is Undefined
      1. USRob W
 

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