_.isLength(value)

142

_.isLength(value)

_.isLength判断一个值是否是一个有效的array-like对象的length属性

是数字且大于0小于Number.MAX_SAFE_INTEGER的整数

参数

value (*): 需要检查的值

返回值

(boolean): 如果value是array-like对象的length返回true，否则false

例子

_.isLength(3);
// => true
 
_.isLength(Number.MIN_VALUE);
// => false
 
_.isLength(Infinity);
// => false
 
_.isLength('3');
// => false

源代码

/** Used as references for various `Number` constants. */
const MAX_SAFE_INTEGER = 9007199254740991

/**
 * Checks if `value` is a valid array-like length.
 *
 * **Note:** This method is loosely based on
 * [`ToLength`](http://ecma-international.org/ecma-262/7.0/#sec-tolength).
 *
 * @since 4.0.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a valid length, else `false`.
 * @example
 *
 * isLength(3)
 * // => true
 *
 * isLength(Number.MIN_VALUE)
 * // => false
 *
 * isLength(Infinity)
 * // => false
 *
 * isLength('3')
 * // => false
 */
//判断一个值是否是一个有效的array-like对象的length属性
//是数字且大于0小于Number.MAX_SAFE_INTEGER的整数
function isLength(value) {
  return typeof value == 'number' &&
    value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER
}

export default isLength