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x/lodash/cond.js

A modern JavaScript utility library delivering modularity, performance, & extras.
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import apply from './_apply.js';import arrayMap from './_arrayMap.js';import baseIteratee from './_baseIteratee.js';import baseRest from './_baseRest.js';
/** Error message constants. */var FUNC_ERROR_TEXT = 'Expected a function';
/** * Creates a function that iterates over `pairs` and invokes the corresponding * function of the first predicate to return truthy. The predicate-function * pairs are invoked with the `this` binding and arguments of the created * function. * * @static * @memberOf _ * @since 4.0.0 * @category Util * @param {Array} pairs The predicate-function pairs. * @returns {Function} Returns the new composite function. * @example * * var func = _.cond([ * [_.matches({ 'a': 1 }), _.constant('matches A')], * [_.conforms({ 'b': _.isNumber }), _.constant('matches B')], * [_.stubTrue, _.constant('no match')] * ]); * * func({ 'a': 1, 'b': 2 }); * // => 'matches A' * * func({ 'a': 0, 'b': 1 }); * // => 'matches B' * * func({ 'a': '1', 'b': '2' }); * // => 'no match' */function cond(pairs) { var length = pairs == null ? 0 : pairs.length, toIteratee = baseIteratee;
pairs = !length ? [] : arrayMap(pairs, function(pair) { if (typeof pair[1] != 'function') { throw new TypeError(FUNC_ERROR_TEXT); } return [toIteratee(pair[0]), pair[1]]; });
return baseRest(function(args) { var index = -1; while (++index < length) { var pair = pairs[index]; if (apply(pair[0], this, args)) { return apply(pair[1], this, args); } } });}
export default cond;