JSFiddle - React, Tailwind, and code Playground

HTML

<div class="block-mother">
  <div class="block">12</div>
  <div class="block">16</div>
  <div class="block">18</div>
  <div class="block">20</div>
  <div class="block">22</div>
</div>

<input id="kek" onchange="updateNumber(event)" type="number" value="10" min="10" max="5000">

JavaScript

const blocks = document.querySelectorAll('.block');
const input = document.querySelector('#kek');
let salesPriceArray = []
let cur = 0;
blocks.forEach(item => {
	salesPriceArray = [+item.innerText, ...salesPriceArray]
})

function updateNumber(event){
	let newValue = event.target.value;
	salesPriceArray.forEach(item => {
  	if(newValue > item){
    	cur = item
    }
  })
  
  console.log(cur)
}