safenum

safenum

Converting a string to a number using JavaScript's built-in parseInt or parseFloat functions may lead to silent failures. For example, invalid characters in the string may be silently ignored, or the resulting number may have less precision than the string representation. This might be fine for some applications, but in other cases an explicit error would be more useful.

With all functions provided by safenum, conversions succeed only when the entire string is consumed during parsing, and the resulting number can be represented exactly as a JavaScript number. If the string contains additional characters, or if the resulting number loses any precision, then conversion fails.

Installation

npm install safenum

Usage

import {parseSafeInt} from 'safenum';

let num1 = parseSafeInt('1337');                // num1 is set to 1337
let num2 = parseSafeInt('123.0');               // throws (didn't consume entire string)
let num3 = parseSafeInt('9007199254740992');    // throws (number is not a SAFE_INTEGER)

API

function parseSafeInt(rawNum: string): number

Parses the string rawNum as an integer number. If parsing consumes the entire string and the resulting value is a SAFE_INTEGER, then the number is returned, otherwise throws a RangeError. If rawNum is not a string, a TypeError is thrown.

function parseSafeFloat(rawNum: string): number

Parses the string rawNum as a floating point number. If parsing consumes the entire string and the resulting value can be represented with no loss of precision, then the number is returned, otherwise throws a RangeError. If rawNum is not a string, a TypeError is thrown.

function tryParseSafeInt(rawNum: string): number

Parses the string rawNum as an integer number. If parsing consumes the entire string and the resulting value is a SAFE_INTEGER, then the number is returned, otherwise returns undefined. Also returns undefined if rawNum is not a string.

function tryParseSafeFloat(rawNum: string): number

Parses the string rawNum as a floating point number. If parsing consumes the entire string and the resulting value can be represented with no loss of precision, then the number is returned, otherwise returns undefined. Also returns undefined if rawNum is not a string.

Development

# build from TypeScript source
npm run build

# run unit tests
npm test

# run benchmarks
npm run bench

License

MIT License. Copyright (c) 2020 Troy Gerwien