You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
69 lines
2.6 KiB
69 lines
2.6 KiB
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;
|
|
|