cast

TL;DR

Node

npm install cast

Ender

ender add cast

Usage

var cast = require('cast');

cast('false', 'boolean'); // will return the boolean false

Intro

Types in JavaScript can be unpredictable, and trying to protect against the edge-cases is a headache. Consider the following:

Booleans

true === "true" // makes sense false !== "false" // ?? false === "" // ?? true === "0" // ?? or any string

Numbers

isNaN(null) // false isNaN(undefined) // true

There are many others, but these conditions make it very difficult to write truly high-level code. This module tries to solve this problem.

The main use case is simplification of form validation/user input. A single call to cast will eliminate the need to do extensive type-checking.

Usage

function cast(val, type[, radix])

• val- the value to cast (strings are the most useful, but integers and arrays can also make sense)
• type- string or function (anything else will throw an exception)
  • if a function, an instanceof will be done internally
  • if a string, acceptable values are: 'array', 'boolean', 'float', 'integer', 'number' (alias for 'float')
• radix- only applies for integers

There are only two possible return values, null or something of the type specified by type. Since null cannot be assigned to (as undefined can), this makes complete sense. The first parameter is never modified, so this function truly does no evil.

Examples

Arrays

cast([], 'array'); // returns [] (same reference) cast('[]', 'array'); // returns [] (from JSON.parse)

Booleans

cast('true', 'boolean'); // returns true cast('false', 'boolean'); // returns false cast(true, 'boolean'); // returns true cast(false, 'boolean'); // returns false

Integers

cast('10', 'integer'); // returns 10 cast('10c', 'integer'); // returns null cast('10e10', 'integer'); // returns null cast(10, 'integer'); // returns 10 cast('10', 'integer', 8); // returns 8 cast('10', 'integer', '8'); // returns 8 cast('10.1', 'integer', 10); // returns null cast('10.1', 'integer'); // returns null

Floats

cast('5.25', 'float'); // returns 5.25

Strings

cast(5, 'string'); // returns '5' cast(true, 'string'; // returns 'true' cast('hello', 'string'); // returns 'hello' cast({}, 'string'); // returns null cast(undefined, 'string'); // returns null cast(null, 'string'); // returns null cast([], 'string'); // returns null