can we add jquery in chrome extension js code
You can just put jquery.js into extension folder and include it in the manifest:
{
"name": "My extension",
...
"content_scripts": [
{
"matches": ["http://www.google.com/*"],
"css": ["mystyles.css"],
"js": ["jquery.js", "myscript.js"]
}
],
...
}
You don't need to worry about conflicts with jQuery on a parent page as content scripts are sandboxed.