polyfill-service/polyfills/Array/prototype/findIndex/polyfill.js

A polyfill combinator

Object.defineProperty(Array.prototype, 'findIndex', {
	configurable: true,
	value: function findIndex(callback) {
		if (this === undefined || this === null) {
			throw new TypeError(this + 'is not an object');
		}

		if (!(callback instanceof Function)) {
			throw new TypeError(callback + ' is not a function');
		}

		var
		object = Object(this),
		scope = arguments[1],
		arraylike = object instanceof String ? object.split('') : object,
		length = Math.max(Math.min(arraylike.length, 9007199254740991), 0) || 0,
		index = -1;

		while (++index < length) {
			if (index in arraylike) {
				if (callback.call(scope, arraylike[index], index, object)) {
					return index;
				}
			}
		}

		return -1;
	},
	writable: true
});