Skip to content

Instantly share code, notes, and snippets.

@mattlundstrom
Last active October 24, 2020 21:30
Show Gist options
  • Save mattlundstrom/8d961b1eaec7ef32412f3c447348be40 to your computer and use it in GitHub Desktop.
Save mattlundstrom/8d961b1eaec7ef32412f3c447348be40 to your computer and use it in GitHub Desktop.
JS function that can only be fired once.
// ONCE
function once(fn, context) {
var result;
return function() {
if(fn) {
result = fn.apply(context || this, arguments);
fn = null;
}
return result;
};
}
// Usage
var canOnlyFireOnce = once(function() {
console.log('Fired!');
});
canOnlyFireOnce(); // "Fired!"
canOnlyFireOnce(); // nada
// POLL
function poll(fn, callback, errback, timeout, interval) {
var endTime = Number(new Date()) + (timeout || 2000);
interval = interval || 100;
(function p() {
// If the condition is met, we're done!
if(fn()) {
callback();
}
// If the condition isn't met but the timeout hasn't elapsed, go again
else if (Number(new Date()) < endTime) {
setTimeout(p, interval);
}
// Didn't match and too much time, reject!
else {
errback(new Error('timed out for ' + fn + ': ' + arguments));
}
})();
}
// Usage: ensure element is visible
poll(
function() {
return document.getElementById('lightbox').offsetWidth > 0;
},
function() {
// Done, success callback
},
function() {
// Error, failure callback
}
);
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment