gistfile1.txt

/*
    Options : 
      - prop      //property being evaluated  
      - context   //context of `prop` so it can be referenced
      - test      //value `prop` is being evaluated for
      - tries     //max number of tries for test
      - interval  //frequency of tries in ms
      - successCB //success callback
      - failureCB //failure callback
*/

var testing = false;

function waitFor ( O ) {
    var
    prop      = O.prop,
    context   = O.context,
    test      = O.test,
    tries     = O.tries || 20,
    interval  = O.interval || 100,
    successCB = O.successCB || function (){},
    failureCB = O.failureCB || function (){},
    hn, _tries = 0, check;
    
    if ( !prop || !context || !( prop in context ) ) return;

    check = function () {
        return context[prop] === test;
    };

  if ( check() ) {
        successCB();
        return;
    }

    hn = setInterval(function(){
        
        if ( check() ) {
            clearInterval(hn);
            successCB();
            return;
        }
        
        if ( !(++_tries < tries) ) {
            clearInterval(hn);
            failureCB();
        }

    }, interval);

};

waitFor({
    prop : "testing",
    context : window,
    test : true,
    tries : 10,
    interval : 1000,
    successCB : function () {
        console.log("success");
    },
    failureCB : function () {
        console.log("failure");
    }
    
});

//testing = true;