JavaScript if statements not functioning

Question

I'm sure there is a perfectly logical explanation to why this isn't working the way I want it to but I am new to JavaScript so would love some help. Is there any reason you would know as to why it prints out yes even when I want it to print out no. Thanks in advance

<script type="text/javascript">
    var username = prompt("What is your VC?");
    if (username = "wow") {
        greeting = document.write("yes");
    } else {
        document.write("no");
    }  
</script>

I. Ahmed · Answer 1 · 2018-03-20T00:22:53.633

2

The = operator is used for assignment, for checking the value you can use ===. So, change the if as follows:

if (username === "wow")

Working code is given below:

var username = prompt("What is your VC?");
if (username === "wow") { 
    greeting = document.write("yes"); 
} else 
{ 
    document.write("no"); 
}

edited Mar 20 '18 at 00:22

answered Mar 20 '18 at 00:16

I. Ahmed

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score 0 · Answer 2 · answered Mar 20 '18 at 00:16

0

Yes. One = is assignment. Two == tests equality. And three === tests strict equality.

var username = prompt("What is your VC?");
if (username === "wow") {
  document.write("yes");
} else {
  document.write("no");
}

answered Mar 20 '18 at 00:16

Elliott Frisch

198,278
20
158
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score 0 · Answer 3 · answered Mar 20 '18 at 00:19

0

When you say:

a = b

You're saying "set a to the value in b."

If you out that in an if statement's expression, it assigns b to a and thrn checks if a's new value is "truthy."

If you want to ask "is a equal to b," you have to say:

a == b

I know that there is a difference between == and ===, but I am not a JavaScript master, so I cannot tell you what the difference is!

answered Mar 20 '18 at 00:19

Sean

265
2
10

2

`===` compares type. `true == "true"`, but `true !== "true"` – ShaneCoder Mar 20 '18 at 00:54

JavaScript if statements not functioning

3 Answers3