debounce.js•1.22 kB
import restArguments from './restArguments.js';
import now from './now.js';
// When a sequence of calls of the returned function ends, the argument
// function is triggered. The end of a sequence is defined by the `wait`
// parameter. If `immediate` is passed, the argument function will be
// triggered at the beginning of the sequence instead of at the end.
export default function debounce(func, wait, immediate) {
var timeout, previous, args, result, context;
var later = function() {
var passed = now() - previous;
if (wait > passed) {
timeout = setTimeout(later, wait - passed);
} else {
timeout = null;
if (!immediate) result = func.apply(context, args);
// This check is needed because `func` can recursively invoke `debounced`.
if (!timeout) args = context = null;
}
};
var debounced = restArguments(function(_args) {
context = this;
args = _args;
previous = now();
if (!timeout) {
timeout = setTimeout(later, wait);
if (immediate) result = func.apply(context, args);
}
return result;
});
debounced.cancel = function() {
clearTimeout(timeout);
timeout = args = context = null;
};
return debounced;
}