Get the time elapsed since the last call to the checkInterval function. Useful for quick profiling tasks.

gistfile1.js

function interval () {
    var lastTime = new Date().getTime() / 1000;

    return function getInterval () {
        var newTime = new Date().getTime() / 1000;
        var delta = newTime - lastTime;
        lastTime = newTime;
        return delta;
    };
}

var checkInterval = interval();

console.log ( checkInterval() );

// do something

console.log ( checkInterval() );