JSFiddle - React, Tailwind, and code Playground

by Fu-Ching Hsiao

HTML

<select id="firstmenu" name="City">
<option value="--">--</option>
<option value="NY">NY</option>
<option value="LA">LA</option>
</select>
<br/>
<select id="secondmenu" name="zipCode">
<option value="--">--</option>
<option value="10001">10001(NY)</option>
<option value="90001">90001(LA)</option>
</select>

JavaScript

window.onload = function() {
	document.getElementById("firstmenu").addEventListener('change',function(e) {ha(e,'firstmenu','secondmenu');}, false);
};

function ha(e,first,second){
	var firstOptions = document.getElementById(first).options;
	var secondOptions = document.getElementById(second).options;
	for(var i = 1, j = firstOptions.length; i < j; i++) {
		secondOptions[i].value = firstOptions[i].value;
		secondOptions[i].text = firstOptions[i].text;
	}
};