_.isArrayLike(value)

129

_.isArrayLike(value)

_.isArrayLike判断一个值是否是一个array-like

规则：不等于null，不是function类型，并且有length属性，length是大于0小于Number.MAX_SAFE_INTEGER的整数

参数

value (*): 需要检查的值

返回值

(boolean): 如果是array-like对象返回true，否则false

例子

_.isArrayLike([1, 2, 3]);
// => true
 
_.isArrayLike(document.body.children);
// => true
 
_.isArrayLike('abc');
// => true
 
_.isArrayLike(_.noop);
// => false

源代码

import isLength from './isLength.js'

/**
 * Checks if `value` is array-like. A value is considered array-like if it's
 * not a function and has a `value.length` that's an integer greater than or
 * equal to `0` and less than or equal to `Number.MAX_SAFE_INTEGER`.
 *
 * @since 4.0.0
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is array-like, else `false`.
 * @example
 *
 * isArrayLike([1, 2, 3])
 * // => true
 *
 * isArrayLike(document.body.children)
 * // => true
 *
 * isArrayLike('abc')
 * // => true
 *
 * isArrayLike(Function)
 * // => false
 */
//判断一个值是否是一个array-like
//规则：不等于null，不是function类型，并且有length属性，length是大于0小于Number.MAX_SAFE_INTEGER的整数
function isArrayLike(value) {
  return value != null && typeof value != 'function' && isLength(value.length)
}

export default isArrayLike

isLength

/** 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