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Subtraction (-)
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Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The subtraction (-) operator subtracts the two operands, producing their difference.
console.log(5 - 3);
// Expected output: 2
console.log(3.5 - 5);
// Expected output: -1.5
console.log(5 - "hello");
// Expected output: NaN
console.log(5 - true);
// Expected output: 4
The - operator is overloaded for two types of operands: number and BigInt. It first coerces both operands to numeric values and tests the types of them. It performs BigInt subtraction if both operands become BigInts; otherwise, it performs number subtraction. A TypeError is thrown if one operand becomes a BigInt but the other becomes a number.
js
5 - 3; // 2
3 - 5; // -2
Other non-BigInt values are coerced to numbers:
js
"foo" - 3; // NaN; "foo" is converted to the number NaN
5 - "3"; // 2; "3" is converted to the number 3
You cannot mix BigInt and number operands in subtraction.
js
2n - 1; // TypeError: Cannot mix BigInt and other types, use explicit conversions
2 - 1n; // TypeError: Cannot mix BigInt and other types, use explicit conversions
To do subtraction with a BigInt and a non-BigInt, convert either operand:
js
2n - BigInt(1); // 1n
Number(2n) - 1; // 1