检查带有Firefox扩展的Javascript是否存在URL

Question

我想使用带有Firefox扩展程序的Javascript检查给定的URL是否存在。

Answer 1

我想你想尝试加载URL - 使用XMLHttpRequest：

var request = new XMLHttpRequest();
request.open("GET", url);
request.onload = function()
{
    if ((request.status >= 200 && request.status < 300) || request.status == 304)
        alert("Exists!");
    else
        alert("HTTP response isn't success, URL doesn't exist or is currently unavailable");
};
request.onerror = function()
{
    alert("Loading URL errored out, server doesn't exist or is currently unavailable");
};
request.send(null);