lodash/internal/isLength.js

define([], function() {

  /**
   * Used as the [maximum length](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-number.max_safe_integer)
   * of an array-like value.
   */
  var MAX_SAFE_INTEGER = Math.pow(2, 53) - 1;

  /**
   * Checks if `value` is a valid array-like length.
   *
   * **Note:** This function is based on [`ToLength`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength).
   *
   * @private
   * @param {*} value The value to check.
   * @returns {boolean} Returns `true` if `value` is a valid length, else `false`.
   */
  function isLength(value) {
    return typeof value == 'number' && value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER;
  }

  return isLength;
});