Use the expression n/n^0.
If n is not zero:
Step Explanation
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n/n^0 Original expression.
1^0 Any number divided by itself equals 1. Therefore n/n becomes 1.
1 1 xor 0 equals 1.
If n is zero:
Step Explanation
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n/n^0 Original expression.
0/0^0 Since n is 0, n/n is 0/0.
NaN^0 Zero divided by zero is mathematically undefined. Therefore 0/0 becomes NaN.
0^0 In JavaScript, before any bitwise operation occurs, both operands are normalized.
This means NaN becomes 0.
0 0 xor 0 equals 0.
As you can see, all non-zero values get converted to 1, and 0 stays at 0. This leverages the fact that in JavaScript, NaN^0 is 0.
Demo:
[0, 1, 19575, -1].forEach(n => console.log(`${n} becomes ${n/n^0}.`))