70 lines
2.6 KiB
JavaScript
70 lines
2.6 KiB
JavaScript
import debounce from './debounce.js';
|
|
import isObject from './isObject.js';
|
|
|
|
/** Error message constants. */
|
|
var FUNC_ERROR_TEXT = 'Expected a function';
|
|
|
|
/**
|
|
* Creates a throttled function that only invokes `func` at most once per
|
|
* every `wait` milliseconds. The throttled function comes with a `cancel`
|
|
* method to cancel delayed `func` invocations and a `flush` method to
|
|
* immediately invoke them. Provide `options` to indicate whether `func`
|
|
* should be invoked on the leading and/or trailing edge of the `wait`
|
|
* timeout. The `func` is invoked with the last arguments provided to the
|
|
* throttled function. Subsequent calls to the throttled function return the
|
|
* result of the last `func` invocation.
|
|
*
|
|
* **Note:** If `leading` and `trailing` options are `true`, `func` is
|
|
* invoked on the trailing edge of the timeout only if the throttled function
|
|
* is invoked more than once during the `wait` timeout.
|
|
*
|
|
* If `wait` is `0` and `leading` is `false`, `func` invocation is deferred
|
|
* until to the next tick, similar to `setTimeout` with a timeout of `0`.
|
|
*
|
|
* See [David Corbacho's article](https://css-tricks.com/debouncing-throttling-explained-examples/)
|
|
* for details over the differences between `_.throttle` and `_.debounce`.
|
|
*
|
|
* @static
|
|
* @memberOf _
|
|
* @since 0.1.0
|
|
* @category Function
|
|
* @param {Function} func The function to throttle.
|
|
* @param {number} [wait=0] The number of milliseconds to throttle invocations to.
|
|
* @param {Object} [options={}] The options object.
|
|
* @param {boolean} [options.leading=true]
|
|
* Specify invoking on the leading edge of the timeout.
|
|
* @param {boolean} [options.trailing=true]
|
|
* Specify invoking on the trailing edge of the timeout.
|
|
* @returns {Function} Returns the new throttled function.
|
|
* @example
|
|
*
|
|
* // Avoid excessively updating the position while scrolling.
|
|
* jQuery(window).on('scroll', _.throttle(updatePosition, 100));
|
|
*
|
|
* // Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes.
|
|
* var throttled = _.throttle(renewToken, 300000, { 'trailing': false });
|
|
* jQuery(element).on('click', throttled);
|
|
*
|
|
* // Cancel the trailing throttled invocation.
|
|
* jQuery(window).on('popstate', throttled.cancel);
|
|
*/
|
|
function throttle(func, wait, options) {
|
|
var leading = true,
|
|
trailing = true;
|
|
|
|
if (typeof func != 'function') {
|
|
throw new TypeError(FUNC_ERROR_TEXT);
|
|
}
|
|
if (isObject(options)) {
|
|
leading = 'leading' in options ? !!options.leading : leading;
|
|
trailing = 'trailing' in options ? !!options.trailing : trailing;
|
|
}
|
|
return debounce(func, wait, {
|
|
'leading': leading,
|
|
'maxWait': wait,
|
|
'trailing': trailing
|
|
});
|
|
}
|
|
|
|
export default throttle;
|