text: /** Used as references for various `Number` constants. */
  const MAX_SAFE_INTEGER = 9007199254740991
  
  /**
   * Checks if `value` is a valid array-like length.
   * 检查变量value是否是一个有效的"类数组类型的长度值"
   *
   * **Note:** This method is loosely based on  此方法松散地基于ecma规范的ToLength
   * [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
   *
   * @since 4.0.0
   * @category Lang
   * @param {*} value The value to check.  要检查的变量
   * @returns {boolean} Returns `true` if `value` is a valid length, else `false`.  如果value是一个有效的长度就返回true，否则返回false
   * @example
   *
   * isLength(3)
   * // => true
   *
   * isLength(Number.MIN_VALUE)
   * // => false
   *
   * isLength(Infinity)
   * // => false
   *
   * isLength('3')
   * // => false
   */
  function isLength(value) {
    // value值需要是：大于-1且小于等于'最大安全整数'的整数
    return typeof value === 'number' &&
      value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER
  }
  
  export default isLength
  