JSFiddle - React, Tailwind, and code Playground

HTML

<div class="field">
  <label for="propertyprice">Price</label>
  <input id="currency" />
    <p class="field_help">Enter only numbers.</p>
</div>

<div class="field">
  <label for="propertypricerange">Price Range </label>
  <select id="propertypricerange" name="propertypricerange" class="medium">
    <optgroup label="Enter Price Range">
      <option value="0">0    -    $100,000</option>
      <option value="100000">$100,000    -    $200,000</option>
      <option value="200000">$200,000    -    $300,000</option>
      <option value="300000">$300,000    -    $400,000</option>
      <option value="400000">$400,000    -    $500,000</option>
      <option value="500000">$500,000    -    $600,000</option>
      <option value="600000">$600,000    -    $700,000</option>
      <option value="700000">$700,000    -    $800,000</option>
      <option value="800000">$800,000    -    $900,000</option>
      <option value="900000">$900,000    -    $1,000,000</option>
      <option value="1000000">$1,000,000    -    $2,000,000</option>
      <option value="2000000">$2,000,000    -    $3,000,000</option>
      <option value="3000000">$3,000,000    -    $4,000,000</option>
      <option value="4000000">$4,000,000    -    $5,000,000</option>
      <option value="5000000">$5,000,000    -    $10,000,000</option>
      <option value="10000000">$10,000,000    -    +</option>
    </optgroup>
  </select>
</div>

JavaScript

//Dropdown option value finder
function findRange() {
  var opts = $('propertypricerange').options;
  var val = $('currency').value;

   for(x=0;x<opts.length;x++) {
    if(opts[x].value*1 <= val*1) {
      $('propertypricerange').selectedIndex = x;
    }
  }
}

$('currency').onkeyup = findRange;