How to make the situation true JAVASCRIPT

Question

I don't know what is the missing code here it's giving me a headache because of the conditional statement.

Add the missing codes so that the condition below will evaluate to TRUE and print “it works!” in the console.

if (num == 100 && num== 200 && num==300) {
    document.write('it works!');
} else {
    document.write('it doesnt');
}

THIS IS YOUR ASSIGNMENT LMAO! anyway, should the codes be added before the conditional statement? — ACD, Mar 29 '19 at 08:40

HMR · Answer 1 · 2019-03-29T08:56:40.433

2

If that's the real question you can do it using valueOf:

    var Num = function() {
      this.values = [100, 200, 300];
      this.index = -1;
    };
    Num.prototype.valueOf = function() {
      this.index++;
      return this.values[this.index];
    };
    var num = new Num();
    if (num == 100 && num == 200 && num == 300) {
      console.log('it works!');
    } else {
      console.log('it doesnt');
    }

It may look like num is 100, 200 and 300 at once but the if statement has 3 expressions: num == 100 then num == 200 and then num == 300. Each time you compare num to a number with type coercion (using == instead of ===) the valueOf will be invoked, that changes inner state of the num object instance so next time you compare it'll produce a different value.

I would not use type coercion comparing == and instead use ===, when you use a linter it will usually complain when using == as it can cause some unexpected behavior and makes your code less predictable.

edited Mar 29 '19 at 08:56

answered Mar 29 '19 at 08:45

HMR

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Wow, so `num` _can_ be 100, 200 and 300 at once! Twisted but impressive solution, have an upvote – Jeremy Thille Mar 29 '19 at 08:48
@JeremyThille Nina actually added a link to similar "solution". valueOf and toString are used in type coercion. – HMR Mar 29 '19 at 08:49
2

You have disproved common sense. Congratulations. – Jack Bashford Mar 29 '19 at 08:51
Ah right, I didn't notice. This is messed up – Jeremy Thille Mar 29 '19 at 08:51

Nina Scholz · Accepted Answer · 2019-03-29T08:41:44.487

1

You need to use logical OR ||, because with logical AND && the condition is never true, if you take the same value of num.

if (num == 100 || num== 200 || num == 300) {

But in Javascript everything is possible, like: Can (a== 1 && a ==2 && a==3) ever evaluate to true?

edited Mar 29 '19 at 08:41

answered Mar 29 '19 at 08:36

Nina Scholz

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Ajay · Answer 3 · 2019-03-29T09:10:10.773

0

It will not satisfy the condition at a time and print "it doesn't". So the solution would be like this. if(num==100 || num==200 || num==300)

edited Mar 29 '19 at 09:10

answered Mar 29 '19 at 08:39

Ajay

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6

Yes but why? And what is the solution? – Jeremy Thille Mar 29 '19 at 08:40
num has a value, and you are using AND operator for three different values, which will never satisfy. – Ajay Mar 29 '19 at 08:43
That's the why, and what is the solution? You have to make a complete answer, not just say "The code doesn't work" – Jeremy Thille Mar 29 '19 at 08:46
Yes I explained, and sometime you should think too. So the solution would be use OR operator if(num==100 || num==200 || num==300) – Ajay Mar 29 '19 at 08:48
I have newly started to answer. Thanks for your guide. – Ajay Mar 29 '19 at 09:11

How to make the situation true JAVASCRIPT

3 Answers3