JSFiddle - React, Tailwind, and code Playground

HTML

<form action="" id="form">
    <select name="min">
        <option value="1200">1200</option>
        <option value="3300">3300</option>
        <option value="4400">4400</option>
        <option value="5500">5500</option>
        <option value="6600">6600</option>
    </select>
    <select name="max">
        <option value="1200">1200</option>
        <option value="3300">3300</option>
        <option value="4400">4400</option>
        <option value="5500">5500</option>
        <option value="6600">6600</option>
    </select>
    <button type="button" id="ok">ok</button>
</form>

JavaScript

document.querySelector('#ok').onclick = function(){
    var min = this.parentNode.querySelector('[name="min"]').value;
    var max = this.parentNode.querySelector('[name="max"]').value;
	if(min > max){
    	alert('min ('+min+') не может быть больше чем max ('+max+')');
    }else{
        alert('все ок');
    }
};