How i can Decrease and Increase a variable in Javascript

Question

How i can increase and decrease a variable in JS? Every time I decrease variable VIDA the decrease of VIDA only applies on Alert, after that VIDA goes back to 3. In my code,the user needs to select 4 radio options and only 1 is correct and in only 3 attempts

var box;
var pontos = 0;
var vida = 3;

function erro() {
  if (vida === 3 || vida === 2) {
    vida--;
    alert('Errow,vidas restantes:' + vida);
  }
  if (vida == 1)
    alert("Perdeu");
}

function acerto() {
  if (vida == "3") {
    pontos += 50;
  }
  if (vida == "2") {
    pontos += 30;
  }
  if (vida == "1") {
    pontos += 10;
  }
  alert("Acertou,numero de pontos:" + pontos);
}


function valida() {
  var perg = document.getElementById('perg').value;
  alert(perg);
  if (document.getElementById('resp1').checked) {
    box = document.getElementById('resp1').value;
  }
  if (document.getElementById('resp2').checked) {
    box = document.getElementById('resp2').value;
  }
  if (document.getElementById('resp3').checked) {
    box = document.getElementById('resp3').value;
  }
  if (document.getElementById('resp4').checked) {
    box = document.getElementById('resp4').value;
  }
  switch (perg) {
    case "1":
      switch (box) {
        case "1":
          acerto();
          break;
        case "2":
          erro();
          break;
        case "3":
          erro();
          break;
        case "4":
          erro();
          break;
      }
      break;
  }
}

<form name="respostas">
  <input id="vida" value="3">
  <input type="hidden" id="perg" value="1">
  <input type="radio" id="resp1" name="resp" value="1">
  <input type="radio" id="resp2" name="resp" value="2">
  <input type="radio" id="resp3" name="resp" value="3">
  <input type="radio" id="resp4" name="resp" value="4">
  <input type="submit" value="submit" onclick="valida()">
</form>

do you have numbers or strings to compare. it would be easier, if numerical looking values are numbers and then check with strict equality. — Nina Scholz, Sep 20 '18 at 21:39
The problem may be somewhere else in your code, this should be decreasing it as far as I can tell. — John Montgomery, Sep 20 '18 at 21:44
@JohnMontgomery in my JS Code i have another function to call this functions,but its alot of code — Josemar Henrique, Sep 20 '18 at 21:54
If that other function interacts with `vida` at any point, that's likely where the problem is. — John Montgomery, Sep 20 '18 at 21:55
@JohnMontgomery i dont think so,the function only checks the forms radio input. — Josemar Henrique, Sep 20 '18 at 22:05
Is any other code using it? There's nothing you've shown here that could increase or reset the value, so either you're not actually seeing the behavior you think you are, or something else is changing it. — John Montgomery, Sep 20 '18 at 22:08
@JohnMontgomery i did an update on code to post the another function who call these — Josemar Henrique, Sep 20 '18 at 22:13
Oh, now that I look at the snippet it's obvious. When you click the button, it's submitting the form which makes the page refresh. Change the form tag to `
` and it works. — John Montgomery, Sep 20 '18 at 23:12
Possible duplicate of [Want html form submit to do nothing](https://stackoverflow.com/questions/3384960/want-html-form-submit-to-do-nothing) — John Montgomery, Sep 20 '18 at 23:13

How i can Decrease and Increase a variable in Javascript

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