| /** Used to detect unsigned integer values. */ |
| var reIsUint = /^\d+$/; |
| |
| /** |
| * Used as the [maximum length](http://ecma-international.org/ecma-262/6.0/#sec-number.max_safe_integer) |
| * of an array-like value. |
| */ |
| var MAX_SAFE_INTEGER = 9007199254740991; |
| |
| /** |
| * Checks if `value` is a valid array-like index. |
| * |
| * @private |
| * @param {*} value The value to check. |
| * @param {number} [length=MAX_SAFE_INTEGER] The upper bounds of a valid index. |
| * @returns {boolean} Returns `true` if `value` is a valid index, else `false`. |
| */ |
| function isIndex(value, length) { |
| value = (typeof value == 'number' || reIsUint.test(value)) ? +value : -1; |
| length = length == null ? MAX_SAFE_INTEGER : length; |
| return value > -1 && value % 1 == 0 && value < length; |
| } |
| |
| module.exports = isIndex; |