If Statement in JavaScript for Getting Value from Select Input

Question

i get stuck with this problem. First, here is the codes :

JavaScript

function PilihKeterangan(isi)
{
    if (isi = 'A') {
        $('#keterangan').val("Sangat Baik : sangat aktif mengikuti latihan dan kegiatan ...");
    } else if (isi = "B") {
        $('#keterangan').val("Baik : aktif mengikuti latihan dan kegiatan ...");
    } else if (isi = 'C') {
        $('#keterangan').val("Cukup : cukup aktif mengikuti latihan dan kegiatan Kepramukaan ..."); 
    } else if (isi = 'X') {
        $('#keterangan').val("Kegiatan ini tidak dipilih oleh siswa / bukan menjadi pilihan siswa");
    } else {
        $('#keterangan').val("Pilihlah predikat A/B/C/X.");
    }

}

HTML

<select class="form-control" name="PREDIKAT_EKSTRA_UTS" onchange="PilihKeterangan(this.value)">
    <option selected value="">- Pilih -</option>
    <option value="A">A</option>
    <option value="B">B</option>
    <option value="C">C</option>
    <option value="X">X</option>
</select>

The problem is, it just can select first condition. If i click other option, the result is still first conddition. In example : If i select/click 'A' or 'B' or else one the result is always first condition. But if i just passing select's value, it is works but not when i give it IF statement.

I just look from this tutorial about using IF statement in w3schools if the JavaScript is using '=' not the '==' : http://www.w3schools.com/js/js_if_else.asp

I hope there are any reply. Thanks :)

Who is giving me -1 score? – Angga Lisdiyanto Feb 17 '15 at 06:57 — Angga Lisdiyanto, Feb 17 '15 at 06:57

score 2 · Accepted Answer · answered Feb 17 '15 at 06:54

2

This is not syntaxt of if statement

you should do like this :

if(isi == 'A'){
    // your code
}

This is called comparison operation : " == "

answered Feb 17 '15 at 06:54

hitesh upadhyay

264
1
9

I would recommend using the identity operator `===` over the equality operator `==`, see http://stackoverflow.com/a/359509/261564 for more info. – Sphvn Feb 17 '15 at 06:59
But in wc3school, they using '=' in IF statement : http://www.w3schools.com/js/js_if_else.asp – Angga Lisdiyanto Feb 17 '15 at 07:03
@AnggaLisdiyanto No, they aren't. – JJJ Feb 17 '15 at 07:05
"==" for equal to and "===" for equal value and equal type – hitesh upadhyay Feb 17 '15 at 07:05
@Juhana is correct, they are using (`>`) and (`<`) and using assignment within the if statement, not actually in the `if ()` statement itself. – Sphvn Feb 17 '15 at 07:06

score 2 · Answer 2 · answered Feb 17 '15 at 06:57

2

as mentioned by hitesh upadhyay and Oliver you should use equality operator == and not assignment operator =.

Consider using switch in this case to produce cleaner code.

function PilihKeterangan(isi)
{
    var msg = "";
    switch(isi){
        case 'A':
            msg = "Sangat Baik : sangat aktif mengikuti latihan dan kegiatan ...";
        break;
        case 'B':
            msg = "Baik : aktif mengikuti latihan dan kegiatan ...";
        break;
        case 'C':
            msg = "Cukup : cukup aktif mengikuti latihan dan kegiatan Kepramukaan ...");
        break;
        case 'X':
            msg = "Kegiatan ini tidak dipilih oleh siswa / bukan menjadi pilihan siswa";
        break;
        default:
            msg = "Pilihlah predikat A/B/C/X.";
        break;
    }
    $('#keterangan').val(msg);
}

answered Feb 17 '15 at 06:57

josegomezr

888
4
15

But in wc3school, they using = in IF statement : http://www.w3schools.com/js/js_if_else.asp – Angga Lisdiyanto Feb 17 '15 at 07:02
w3schools is not always correct or affiliated in any way with the W3C please do not take it as an absolute source. – Sphvn Feb 17 '15 at 07:02
So like that? So who is wc3school? – Angga Lisdiyanto Feb 17 '15 at 07:06
@AnggaLisdiyanto It's a private company who's using a misleading name on purpose. And it's w3schools, not wc3school. – JJJ Feb 17 '15 at 07:08
Thanks for all your reply guys. :) – Angga Lisdiyanto Feb 17 '15 at 07:14

score 1 · Answer 3 · edited May 23 '17 at 10:24

This would be because you are using the assignment operator (=) rather than an equality operator (==), I would generally suggest using the identity operator (===).

The if clause must return a boolean value, an assignment does not.

The identity (===) operator behaves identically to the equality (==) operator except no type conversion is done, and the types must be the same to be considered equal.

This is covered extensively on this Stack Overflow answer

score 0 · Answer 4 · answered Feb 17 '15 at 06:54

0

You are using a single = you need to use a == for equality

answered Feb 17 '15 at 06:54

Oliver

35,233
12
66
78

Okay, but in wc3school, they using '=' in IF statement : http://www.w3schools.com/js/js_if_else.asp – Angga Lisdiyanto Feb 17 '15 at 07:03

If Statement in JavaScript for Getting Value from Select Input

JavaScript

HTML

4 Answers4