Amazon to eBay Firefox Automatic Link Generator Add-on/Extension

The following extension adds a link to the eBay search page on the Amazon product page for the product being viewed for comparison. Clicking on the link opens a new tab with eBay search results for the Amazon product. 

Create a folder named amazon_ebay and add the following manifest.json and amazon_ebay.js files to this folder.

	{
	"manifest_version": 2,
	"name": "Amazon To Ebay",
	"version": "1.0",
	"description": "Adds a link to eBay search results from the Amazon product page for price comparison.",
	"content_scripts": [
	{
	"matches": ["*://*.amazon.com/*"],
	"js": ["amazon_ebay.js"]
	}
	]
	}

view raw manifest.json hosted with ❤ by GitHub

	doc = document.getElementById("productTitle");
	try{
	var ebay = "https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=" + doc.innerHTML;
	var node = document.createElement("a");
	node.href = ebay;
	node.target = "_blank";
	var textnode = document.createTextNode("eBay");
	node.appendChild(textnode);
	var pnode = document.createElement("p");
	doc.appendChild(pnode);
	doc.appendChild(node);
	var pnode = document.createElement("p");
	doc.appendChild(pnode);
	}
	catch(err){
	}

view raw amazon_ebay.js hosted with ❤ by GitHub

Go to about:debugging in Firefox and click Load Temporary Add-on and load the manifest.json file.

Then visit a product page on Amazon (amazon.com) and there will be a link 'eBay', just below the product title, pointing to the corresponding search results in eBay (ebay.com). By making appropriate changes to the manifest.json and amazon_ebay.js files you can get this extension to work on Amazon/eBay of different countries.