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nicks-cors-test

★ 125 Open GitHub ↗

Simple HTML & JS Tool to quickly test CORS locally.

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# nicks-cors-test
Simple HTML & JS Tool to quickly test CORS locally.

# Blog
https://medium.com/pareture/simple-local-cors-test-tool-544f108311c5

# CORS
Cross Origin Resource Sharing (CORS) is a simple and powerful mechanism which uses HTTP headers so that a server knows where a request is coming from and can choose whether or not to accept the request based on this.

Better information here:
https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS

The header which is provided as the argument is the ‘Origin’. This is set by the User-Agent (the thing that makes the request) and can not be overridden (security enforced).

The server with the resource uses the `Access-Control-Allow-Origin` header to allowlist particular domains or allow requests from all origins using the wildcard:
```
Access-Control-Allow-Origin: *
```

# Tool
You can use this simple tool to test making CORS requests and examine the outcome.

* The HTML file is simply a shell to call the Javascript function.
* The JS file executes an AJAX request based on the values you adjust.

# Guide
* Download the files and open `index.html` in a browser. You will be faced with a blank screen and nothing else.
* Open the browser tools: e.g **Right-click** > **Inspect** > **Console**.
* Open `main.js` file in a text editor.
* Adjust the `url` value depending on the resource you want to check, save `main.js` and refresh the browser. 
    * Try `https://google.com` and you will see it has been blocked due to CORS.
    * Try `https://api.github.com` and you will see it is not blocked and the content will be output.

nicks-cors-test

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