JSFiddle - React, Tailwind, and code Playground

by patilanz

HTML

<select id="campo" name="campo" onchange="comprobar();">
    <option value="uno">uno</option>
    <option value="dos">dos</option>
    <option value="tres">tres</option>
</select>

op1
<input type="checkbox" name="op1" id="op1" value="1" />

op2
<input type="checkbox" name="op2" id="op2" value="2" />

op3
<input type="checkbox" name="op3" id="op3" value="3" />

op4
<input type="checkbox" name="op4"  id="op4" value="4" />

op5
<input type="checkbox" name="op5" id="op5" value="5" />

JavaScript

function comprobar(){
	for(var b=1;b<6;b++){
		document.getElementById('op'+b).checked=false;
	}
	var a=document.getElementById('campo');
	a=a.options[a.selectedIndex].value;
	if(a=='uno'){
		document.getElementById('op1').checked=true;
	}
	if(a=='dos'){
		document.getElementById('op3').checked=true;
		document.getElementById('op5').checked=true;
	}
}