strto.js

strto is a strict string-to-number conversion library that works in node and browsers. strto is tiny, adding ~300 bytes to your gzipped payload.

Usage

var strto = require("strto"); // or include strto.js in a <script> tag

Examples

var n = strto.safeint(stringifiedNumber, null);
if (n !== null) {
    // n is an integer number in the range [-9007199254740991, 9007199254740991]
}

// errval can be used as a default value when that fits your code
n = strto.inexactint(formval.trim(), 0);
// n is an integer number and it may or may not be outside of range
// [-9007199254740991, 9007199254740991] thus inexact, even +-Infinity, but never NaN.

// errval can be any value, if you dislike null
var nil = {toString: function() { bomb }, valueOf: function() { bomb }};
n = strto.finitefloat(formval.trim(), nil);
if (n !== nil) {
    // n is an integer or floating point number, anything except +-Infinity or NaN
}
n = strto.float(formval.trim(), nil);
if (n !== nil) {
    // n may be any JS number (integer, floating point, +-Infinity and NaN)
}

// errval can be NaN if you want that monster back
n = strto.float(formval.trim(), NaN);
// whatever

Exceptions

All functions throw exceptions if str is not a string or if errval is missing. This is to help you catch errors early in development. You're not supposed to try-catch these.

strto.safeint(str: string, errval: any): (number | errval)

strto.safeint converts a string that apart from digits may only contain an optional leading - (no ., +, whitespace or any other characters). Put another way, str must match /^-?[0-9]+$/. If such a string is possible to convert exactly to a JavaScript integer number, i.e. it fits within the range [-9007199254740991, 9007199254740991], then that number will be returned. In all other cases (be it out of range or invalid string characters), errval will be returned. The base is always 10. Negative zero (a floating point peculiarity) will be normalized to integer zero.

strto.inexactint(str: string, errval: any): (number | errval)

strto.inexactint is like strto.safeint except it does not require the return value to fit within the range [-9007199254740991, 9007199254740991]. This means that strto.inexactint("123456789123456789", null) returns a non-null value that is roughly (but not exactly) similar to 123456789123456789. It also means that strto.inexactint(new Array(400).join("1"), null) returns Infinity. It can however never return NaN or negative zero.

strto.finitefloat(str: string, errval: any): (number | errval)

strto.finitefloat converts a string in scientific notation format to a JavaScript number. This is the everyday floating point notation you're used to in JavaScript and base-10 integers are a subset of it. Valid examples are "+1", "-0", "15e4", "0.3", ".3", ".3e3", ".3e+3" and ".3e-3". The string can't contain whitespace or any other characters not belonging to the number. Put another way, str must match /^[-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?$/. If such a string is possible to convert to a finite number, i.e. any number that isn't -Infinity, Infinity or NaN, then that number is returned. In all other cases, errval will be returned.

strto.float(str: string, errval: any): (number | errval)

strto.float is like strto.finitefloat except it does not require the return value to be finite, so -Infinity, Infinity and NaN are also possible return values. Put another way, str must match /^([-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?|Infinity|-Infinity|NaN)$/.

Installation

Node

Install using npm

npm install strto

var strto = require("strto");

Browser

Install using npm

npm install strto

<script src="node_modules/strto/strto.min.js"></script>