_.minBy(array, [iteratee=_.identity])

182

_.minBy(array, [iteratee=_.identity])

_.minBy此方法类似min，区别是接收一个iteratee为每一个数组元素调用去根据每个值的排列生成对应的标准值

参数

array (Array): 需要被迭代的数组
[iteratee=_.identity] (Function): 对每一个元素调用生成标准值的迭代器函数

返回值

(*): 返回数组最小值

例子

 

var objects = [{ 'n': 1 }, { 'n': 2 }];
 
_.minBy(objects, function(o) { return o.n; });
// => { 'n': 1 }
 
// The `_.property` iteratee shorthand.
_.minBy(objects, 'n');
// => { 'n': 1 }

 

源代码

import isSymbol from './isSymbol.js'

/**
 * This method is like `min` except that it accepts `iteratee` which is
 * invoked for each element in `array` to generate the criterion by which
 * the value is ranked. The iteratee is invoked with one argument: (value).
 *
 * @since 4.0.0
 * @category Math
 * @param {Array} array The array to iterate over.
 * @param {Function} iteratee The iteratee invoked per element.
 * @returns {*} Returns the minimum value.
 * @example
 *
 * const objects = [{ 'n': 1 }, { 'n': 2 }]
 *
 * minBy(objects, ({ n }) => n)
 * // => { 'n': 1 }
 */
//此方法类似min，区别是接收一个iteratee为每一个数组元素调用去根据每个值的排列生成对应的标准值
function minBy(array, iteratee) {
  let result//最小值结果
  if (array == null) {//如果数组为null，返回undefined
    return result
  }
  for (const value of array) {//循环数组
    let computed//中间变量存下当前最小值的标准值
    const current = iteratee(value)//当前循环元素的标准值

    if (current != null && (computed === undefined
          ? (current === current && !isSymbol(current))
          : (current < computed)
        )) {
           //如果current不是null且computed还没有值，并且current不是NaN且不是Symbol对象，就创建computed和result存下当前current
          //否则就用comparator比较current和computed的大小
      computed = current
      result = value
    }
  }
  return result
}

export default minBy