Question

I have below array

const floorPerDayMilestones = [25, 50, 75, 100, 125, 150, 175, 200]

From the frontEnd user enters any number say it is

const number = 136

I need to find closest to the number but the lesser one. So the output should be 125

Even if the number is 149 the output should be 125

How can I do this. I tried many way but could get the answer.

Thanks!!!

Answer 1

If it's sorted in ascending order like in the question this should work.

const floorPerDayMilestones = [25, 50, 75, 100, 125, 150, 175, 200];
const number = 136;

function findClosest(arr, num) {
  for (let i = 0; i < arr.length; ++i) {
    if (arr[i] > num) {
      return arr[i - 1];
    }
  }
}

console.log(findClosest(floorPerDayMilestones,number));

Answer 2

You can use Array.reduce for this

const floorPerDayMilestones = [25, 50, 75, 100, 125, 150, 175, 200]

function getClosestNumber(d) {
  return floorPerDayMilestones.reduce((a, b) => b <=d && a < b ? b : a, 0 )
}

console.log(getClosestNumber(135) || 'No lesser number available')

console.log(getClosestNumber(149) || 'No lesser number available')

console.log(getClosestNumber(22) || 'No lesser number available')

Answer 3

Maybe you should look at this: get closest number out of array

And in your foreach, save your closest number in a var. Then check if your number is bigger than the one in your array . if yes, take your last var, else continue your foreach

Answer 4

Try this

const floorPerDayMilestones = [25, 50, 75, 100, 125, 150, 175, 200];
    
const number = 136;
    
    
const nextLesser = floorPerDayMilestones.reduce((nl, curr) => (curr <= number) && (curr > nl) ? curr : nl , 0)

console.log(nextLesser)

Used Array.prototype.reduce

Answer 5

You can sort the array in ascending order and then find the index of number that is immediately higher than number then one position less of that value will be the immediate number that is less than number

const floorPerDayMilestones = [25, 50, 75, 100, 125, 150, 175, 200]
const number = 136;
floorPerDayMilestones.sort((a,b)=> a-b);
var index = floorPerDayMilestones.findIndex(val => val>number);
var num = floorPerDayMilestones[index-1];
console.log(num);

Answer 6

您还可以过滤出大于给定的数字，并从该子集中选择最大值。

const floorPerDayMilestones = [25, 50, 75, 100, 125, 150, 175, 200]

const number = 136

const filtered = floorPerDayMilestones.filter(el=>el<=number);

console.log(Math.max(...filtered))

或者，如果您已经在使用lodash（仅在这种情况下-不要导入lodash只是为了使用下面的解决方案），则可以使用maxBy来实现。 maxBy将大于number的数字视为null。

const floorPerDayMilestones = [25, 50, 75, 100, 125, 150, 175, 200]

const number = 136

let result = _.maxBy(floorPerDayMilestones, el=>el<=number?el:null);

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>

Answer 7

使用lodash，您可以使用_.sortedIndex：

const numbers = [25, 50, 75, 100, 125, 150, 175, 200]

const closestNum = (arr, n) => {
  let index = _.sortedIndex(arr, n)
  return arr[index] == n ? arr[index] : arr[index-1]
}

console.log(closestNum(numbers, 135))  // 120
console.log(closestNum(numbers, 160))  // 150
console.log(closestNum(numbers, 180))  // 175

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.min.js"></script>

使用JS，您只需使用Array.reduceRight：

const numbers = [25, 50, 75, 100, 125, 150, 175, 200]

const closestNum = (arr, n) => arr.reduceRight((r,c) => !r && c < n ? c : r, 0)

console.log(closestNum(numbers, 135))  // 120
console.log(closestNum(numbers, 160))  // 150
console.log(closestNum(numbers, 180))  // 175

由于它将从右侧开始，因此您所关心的就是找到小于参数n的第一个数字。

您还可以执行Array.reverse，然后执行Array.filter（如果不想mutate使用数组，请使用Array.from）：

const numbers = [25, 50, 75, 100, 125, 150, 175, 200]

const closestNum = (arr, n) => arr.reverse().find(x => x < n)

// To not mutate use `Array.from`
// const closestNum = (arr, n) => Array.from(arr).reverse().find(x => x < n)

console.log(closestNum(numbers, 135))  // 120
console.log(closestNum(numbers, 160))  // 150
console.log(closestNum(numbers, 180))  // 175

Find closest to the number inside array

7 个答案: