_.differenceWith(array, [values], [comparator])

6

_.differenceWith(array, [values], [comparator])

_.differenceWith方法和_.difference方法类似，都是求数组的差集，区别是_.differenceWith接收一个comparator参数作为比较元素值的方法。最终的结果数组取决于第一个参数array。comparator方法有两个参数，arrVal和OthVal。

参数

array (Array): 用来检查的数组
[values] (...Array): 用来排除的数组
[comparator] (Function): 比较array和values元素值的方法

返回值

(Array):返回一个包含过滤值的新数组

例子

var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
 
_.differenceWith(objects, [{ 'x': 1, 'y': 2 }], _.isEqual);
// => [{ 'x': 2, 'y': 1 }]

源代码：

import baseDifference from './.internal/baseDifference.js'
import baseFlatten from './.internal/baseFlatten.js'
import isArrayLikeObject from './isArrayLikeObject.js'
import last from './last.js'

/**
 * This method is like `difference` except that it accepts `comparator`
 * which is invoked to compare elements of `array` to `values`. The order and
 * references of result values are determined by the first array. The comparator
 * is invoked with two arguments: (arrVal, othVal).
 *
 * **Note:** Unlike `pullAllWith`, this method returns a new array.
 *
 * @since 4.0.0
 * @category Array
 * @param {Array} array The array to inspect.
 * @param {...Array} [values] The values to exclude.
 * @param {Function} [comparator] The comparator invoked per element.
 * @returns {Array} Returns the new array of filtered values.
 * @example
 *
 * const objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]
 *
 * differenceWith(objects, [{ 'x': 1, 'y': 2 }], isEqual)
 * // => [{ 'x': 2, 'y': 1 }]
 */
//类似difference方法，求数组的差集，区别是提供了comparator参数，是一个比较方法，在数组元素比较的时候用提供的comparator参数来比较
function differenceWith(array, ...values) {
  let comparator = last(values)//最后一个参数是comparator
  if (isArrayLikeObject(comparator)) {//如果比较器是一个array-like对象，就赋值为undefined
    comparator = undefined
  }
  return isArrayLikeObject(array)
    ? baseDifference(array, baseFlatten(values, 1, isArrayLikeObject, true), undefined, comparator)
    : []
    //如果起始数组array不是array-like对象，就返回空数组
    //如果是array-like对象，就调用baseDifference方法
    //第一个参数是array起始数组，第二个参数是用来排除的数组values展开一层后的数组，第三个参数是迭代器赋值为undefined，第四个参数是比较器
}

export default differenceWith

源码的其他部分和_.difference一样，这里省略