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JavaScript - what operator (== or ===) is used by switch statement to compare?
1 answers
8 points
As in the question title: What operator (== or ===) is used by switch statement to compare?
Is it safe to compare different objects using switch statement?
What about?:
xxxxxxxxxx1
switch (object) {2
// ...3
case object1:4
// ...5
break;6
case object2:7
// ...8
break;9
case object3:10
// ...11
break;12
// ...13
default:14
// ...15
break;16
}
1 answer
4 points
The switch statement compares variables by values and its types, so it behaves like === operator and is safe when compare different objects.
e.g. 1:
xxxxxxxxxx1
const object1 = {2
toString: () => 'Object 1'3
};4
const object2 = {5
toString: () => 'Object 2'6
};7
8
const object = object1;9
10
switch (object) {11
case object1: console.log('`===` operator was used with `object1`.'); break;12
case object2: console.log('`===` operator was used with `object2`.'); break;13
case 'Object 1': console.log('`toString()` method was used with `object1`.'); break;14
case 'Object 2': console.log('`toString()` method was used with `object2`.'); break;15
default:16
throw new Error('Switch statement is not able to compare object in the correct way.');17
}Expected output:
xxxxxxxxxx1
`===` operator was used with `object1`.
e.g. 2:
xxxxxxxxxx1
const object1 = {2
toString: () => 'Object 1'3
};4
const object2 = {5
toString: () => 'Object 2'6
};7
8
const object = object1;9
10
switch (object) {11
case 'Object 1': console.log('`toString()` method was used with `object1`.'); break;12
case 'Object 2': console.log('`toString()` method was used with `object2`.'); break;13
case object1: console.log('`===` operator was used with `object1`.'); break;14
case object2: console.log('`===` operator was used with `object2`.'); break;15
default:16
throw new Error('Switch statement is not able to compare object in the correct way.');17
}Expected output:
xxxxxxxxxx1
`===` operator was used with `object1`.
e.g. 3:
xxxxxxxxxx1
const value = '1';2
3
switch (value) {4
case 1:5
console.log('Case 1 detected.');6
break;7
case '1':8
console.log('Case 2 detected.');9
break;10
default:11
throw new Error('Switch statement is not able to compare values in the correct way.');12
}Expected output:
xxxxxxxxxx1
Case 2 detected.
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