locutus
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Locutus other languages' standard libraries to JavaScript for fun and educational purposes
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JavaScript
export function ParseFloat(s, bitSize) {
// discuss at: https://locutus.io/golang/strconv/ParseFloat
// parity verified: Go 1.23
// original by: Kevin van Zonneveld (https://kvz.io)
// note 1: Parses a floating-point number from string input.
// note 1: Returns [value, null] on success, [0, error] on invalid syntax.
// note 2: Includes edge cases adapted from Go's src/strconv/atof_test.go.
// example 1: ParseFloat('3.14159', 64)[0]
// returns 1: 3.14159
// example 2: ParseFloat('-1.5e2', 64)[0]
// returns 2: -150
// example 3: ParseFloat('bad', 64)[0]
// returns 3: 0
// example 4: ParseFloat('99999999999999974834176', 64)[0]
// returns 4: 9.999999999999997e+22
const value = String(s).trim();
const bits = Math.trunc(Number(bitSize));
if (bits !== 32 && bits !== 64) {
return [0, new Error('strconv.ParseFloat: invalid bitSize')];
}
if (/^[+-]?(?:inf(?:inity)?|nan)$/i.test(value)) {
return [Number(value), null];
}
const isValidFloatLiteral = /^[+-]?(?:\d+(?:\.\d*)?|\.\d+)(?:[eE][+-]?\d+)?$/;
if (!isValidFloatLiteral.test(value)) {
return [0, new Error(`strconv.ParseFloat: parsing "${value}": invalid syntax`)];
}
const parsed = Number.parseFloat(value);
if (Number.isNaN(parsed)) {
return [0, new Error(`strconv.ParseFloat: parsing "${value}": invalid syntax`)];
}
return [bits === 32 ? Math.fround(parsed) : parsed, null];
}