How to increase or decrease values continuously in JavaScript

Question

When mouse click and hold in the element plus, i want to increase or decrease the values, it is working but don't work on mouse hold

var salainv = document.getElementById("sala").value;
var bodegainv = document.getElementById("bodega").value;

function incrementar() {
  document.getElementById("sala").value = salainv++;
  document.getElementById("bodega").value = bodegainv--;
}

function decrementar() {
  document.getElementById("sala").value = salainv--;
  document.getElementById("bodega").value = bodegainv++;
}

<input type="number" name="bodega" id="bodega" value="15">
<input type="number" name="sala" id="sala" value="5">
<img src="https://cdn.pixabay.com/photo/2012/04/13/00/21/plus-31216_960_720.png" style="width: 40px;" onClick="incrementar()">
<img src="http://images.clipartpanda.com/minus-clipart-RTA7dagTL.png" style="width: 40px;" onClick="decrementar()">

Can somebody help me to make it work when mouse is pressed?

Thanks.

Answer 1

You can use setInterval as demonstrated below along with onMouseDown and onMouseUp events

var salainv = document.getElementById("sala").value;
var bodegainv   = document.getElementById("bodega").value;

var timerId;
function incrementar() {
      document.getElementById("sala").value = salainv++;    
      document.getElementById("bodega").value = bodegainv--; 
 }
 function beginIncrementar(){
     timerId = setInterval(incrementar,200);
 }
 function endIncrementar(){
     clearInterval(timerId)
 }
 function decrementar() {
      document.getElementById("sala").value = salainv--;
      document.getElementById("bodega").value = bodegainv++; 
 }
 
 function beginDecrementar(){
     timerId = setInterval(decrementar,200);
 }
 function endDecrementar(){
     clearInterval(timerId)
 }

<input type="number" name="bodega" id="bodega" value="15">
<input type="number" name="sala" id="sala" value="5">
<img src="https://cdn.pixabay.com/photo/2012/04/13/00/21/plus-31216_960_720.png" style="width: 40px;" onClick="incrementar()" onMouseDown="beginIncrementar()" onMouseUp="endIncrementar()">
<img src="http://images.clipartpanda.com/minus-clipart-RTA7dagTL.png" style="width: 40px;" onClick="decrementar()" onMouseDown="beginDecrementar()" onMouseUp="endDecrementar()">