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yanzong_qianduan/node_modules/lodash/before.js

41 lines
1.1 KiB

8 months ago
var toInteger = require('./toInteger');
/** Error message constants. */
var FUNC_ERROR_TEXT = 'Expected a function';
/**
* Creates a function that invokes `func`, with the `this` binding and arguments
* of the created function, while it's called less than `n` times. Subsequent
* calls to the created function return the result of the last `func` invocation.
*
* @static
* @memberOf _
* @since 3.0.0
* @category Function
* @param {number} n The number of calls at which `func` is no longer invoked.
* @param {Function} func The function to restrict.
* @returns {Function} Returns the new restricted function.
* @example
*
* jQuery(element).on('click', _.before(5, addContactToList));
* // => Allows adding up to 4 contacts to the list.
*/
function before(n, func) {
var result;
if (typeof func != 'function') {
throw new TypeError(FUNC_ERROR_TEXT);
}
n = toInteger(n);
return function() {
if (--n > 0) {
result = func.apply(this, arguments);
}
if (n <= 1) {
func = undefined;
}
return result;
};
}
module.exports = before;