Why is my comparison not producing the expected result?

Question

I'm expecting this to output "Failed" but instead it outputs "Excellent", even though the value being compared doesn't match that comparison.

What's wrong with my code?

 let grade = 99; if(140 <= grade <= 150) { console.log('Excellent'); } else if(100 <= grade) { console.log('Very Good'); } else if(grade < 100) { console.log('Failed'); }

Answer 1

This is not how multiple comparisons are made:

if (140 <= grade <= 150)

In this case the first half would evaluate to true or false and the rest would be something like true <= 150 which makes little sense.

Instead, rather than think of it in terms of intuition, think of it in terms of combining logical operations. The two operations you want are:

• 140 <= grade
• grade <= 150

Combine those with the "and" operator:

if (140 <= grade && grade <= 150)

Result:

 let grade = 99; if (140 <= grade && grade <= 150) { console.log('Excellent'); } else if(100 <= grade) { console.log('Very Good'); } else if(grade < 100) { console.log('Failed'); }

Answer 2

If you meant to check whether the grade is between 140 and 150 by 140 <= grade <= 150 then you are doing it the wrong way. This will evaluate 140 <= grade first, which will return either zero or one, which will then be compared to 150 (and hence will always be smaller). You need to use two separate statements:

if(140 <= grade && grade <= 150) {
  ...
}

Answer 3

Do it like this. You need to separate two condition which you provided in the first if statement.

 let grade = 99; if(140<= grade && grade <=150){ console.log('Excellent'); } else if(100<= grade){ console.log('Very Good'); } else if(grade < 100){ console.log('Failed'); }

Answer 4

Expression 140 <= grade <= 150 is correct in mathematical form. In js you must write it as 140 <= grade && grade <=150