If then else using javascript

Question

I have been playing around with the script and can't get it working. It always defaults to option3.

Can anyone help?

<select id="select">
  <option>Please select</option>
  <option value="option1">option1</option>
  <option value="option2">option2</option>
  <option value="option3">option3</option>
</select>
<div id="demo"></div>

<script>

document.getElementById("select").addEventListener("change", myFunction);

function myFunction() {
    if (document.getElementById("select").value = "option1") {
    option = "option 1 chosen";
    }
    if (document.getElementById("select").value = "option2") {
    option = "option 2 chosen";
    }
    if (document.getElementById("select").value = "option3") {
    option = "option 3 chosen";
    }
    document.getElementById("demo").innerHTML = option;
}

</script>

In all your if queries is the sigle equals sign wrong. It must be `==`instead of `=` — Reporter, Sep 21 '16 at 15:54
The condition has assignment statement not comparison statement. Kindly learn correctly. — Praveen Kumar Purushothaman, Sep 21 '16 at 15:54
I disagree that this question is a dupe of the question is was closed in favor of. — j08691, Sep 21 '16 at 15:55
@j08691 I agree with you... Until you find a dupe, let it be closed for the enormous number of answers that say the contents of the above comment. — Praveen Kumar Purushothaman, Sep 21 '16 at 15:58

score 1 · Accepted Answer · edited Jan 20 '19 at 07:22

1

The = assignment operator is used to assign values to a variable to the left of the sign. The == abstract equality operator or === strict equality operator is used to compare values.

function myFunction() {
  if(document.getElementById('select').value === 'option1') {
    option = 'option 1 choosen';
  }
  if(document.getElementById('select').value === 'option2') {
    option = 'option 2 choosen';
  }
  if(document.getElementById('select').value === 'option3') {
    option = 'option 3 choosen';
  }
  document.getElementById("demo").innerHTML = option;
}

edited Jan 20 '19 at 07:22

Patrick Roberts

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answered Sep 21 '16 at 15:54

I think you mean `==`, not `===`. – Wes Foster Sep 21 '16 at 15:55
3

no, "==" is truthy, in all professional code I have done "===" is the preferred method. http://stackoverflow.com/questions/5323377/difference-between-and-in-js – Sep 21 '16 at 15:57
1

No. `==` is standard for comparing values. `===` is standard for comparing the value AND the type. In this instance, he's comparing values. **For example** Given that `x = 5`, `x == "5"` is true. `x === "5"` is false. – Wes Foster Sep 21 '16 at 15:59
1

all well and good. In the company I work for, "==" would fail code review. It might be technically correct....but it practice...it isn't. – Sep 21 '16 at 16:00
1

@E.Maggini don't be bullied into accepting edits that conflict with your intent. You're absolutely right. – Patrick Roberts Jan 20 '19 at 07:11

If then else using javascript

1 Answers1