学步园

manifest.json:

{
"name": "my first Chrome extension",
"manifest_version": 2,
"version": "1.0",

"description": "my first Chrome extension, not bad",
"content_scripts": 
    [
{
"matches": ["*"],
"js": ["func.js"]
}
    ],
"browser_action": 
{
"default_icon": "icon.gif",
"default_popup": "popup.html"
}
}

fun.js:

function reverse()
{
var tmp = v;
v = "";
v = v.concat(tmp.substr(0, 1));
for (var i=tmp.length-1; i>0; i--)
{
v=v.concat(tmp.substr(i, 1));
}
}

var x = document.getElementsByTagName("code");

var v = x[0].innerHTML;
reverse();
alert(v);