The JavaScript exception "invalid BigInt syntax" occurs when a string value is being coerced to a BigInt but it failed to be parsed as an integer.

Message

SyntaxError: Cannot convert x to a BigInt (V8-based)
SyntaxError: invalid BigInt syntax (Firefox)
SyntaxError: Failed to parse String to BigInt (Safari)

Error type

SyntaxError.

What went wrong?

When using the BigInt() function to convert a string to a BigInt, the string will be parsed in the same way as source code, and the resulting value must be an integer value.

Examples

Invalid cases

const a = BigInt("1.5");
const b = BigInt("1n");
const c = BigInt.asIntN(4, "8n");
// SyntaxError: invalid BigInt syntax

Valid cases

const a = BigInt("1");
const b = BigInt("  1   ");
const c = BigInt.asIntN(4, "8");

See also

• BigInt