CODEWITHSUNDEEP
javascripthtml
Cristian Contreras
Cristian Contreras

Reputation: 27

How to increase or decrease values continuously in JavaScript

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.

Upvotes: 3

Views: 860

Answers (3)

Ali Sheikhpour
Ali Sheikhpour

Reputation: 11055

To be more reliable about @Jamiec's answer, I also added onMouseOut because when you start mouseDown (without any mouseUp) and move your mouse out of the trigger, the incrementar or decerementar won't stop anymore:

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)
 }
a{
  display:inline-block;
  border:1px solid #aaaaaa;
  padding:10px;
 }
<input type="number" name="bodega" id="bodega" value="15">
<input type="number" name="sala" id="sala" value="5">
<a onMouseOut="endIncrementar()" onClick="incrementar()" onMouseDown="beginIncrementar()" onMouseUp="endIncrementar()">+</a>
<a onMouseOut="endDecrementar()" onClick="decrementar()" onMouseDown="beginDecrementar()" onMouseUp="endDecrementar()">-</a>

Upvotes: 0

Pugazh
Pugazh

Reputation: 9561

Use setInterval() and clearInterval() on onmousedown and onmouseupevents. Check below example.

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

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

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

function mouseDown(v) {
  if (v == 'inc')
    timer = setInterval(incrementar, 100);
  else
    timer = setInterval(decrementar, 100);
}

function mouseUp(v) {
  clearInterval(timer);
  timer = null;
}
<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="mouseDown('inc')" onmouseup="mouseUp('inc')">
<img src="http://images.clipartpanda.com/minus-clipart-RTA7dagTL.png" style="width: 40px;" onClick="decrementar()" onmousedown="mouseDown('dec')" onmouseup="mouseUp('dec')">

Upvotes: 0

Jamiec
Jamiec

Reputation: 136124

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()">

Upvotes: 4

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