Poll for jQuery until it is loaded

Poll.js

// Source: http://stackoverflow.com/a/17914854/381150
// Sometimes you don't have control over a web page and you need to inject some scripts which are dependent on jQuery. 
// However, this will throw a jQuery/$ undefined error and so the only solution is to poll until it's available.
function defer(method) {
    if (window.jQuery)
        method();
    else
        setTimeout(function() { defer(method) }, 50);
}

//you can use it like
window.xyz = function(){
.... //same stuff as above
}