types.js

types.js

A tiny (1.7kb), but essential Javascript type checking library.

Especially in non-typed scripting languages like Javascript, proper manual type checking is crucial. Because type checking in Javascript is such a mess, I decided to make a library with clear standards I can build upon.

Standard Javascript (NaN == NaN) == false still freakes me out, it's so wrong..
You cannot add to NaN, that's logical. But if (typof NaN == 'number') how can we know if our value is a number?
Well: (value == value), because (NaN != NaN), omg! I refuse to have this in my code, except for this library!

With types.js:

_.typeof( parseInt('Not A Number!') )	// 'nan'
_.typeof( [] );							// 'array'
_.typeof( null );						// 'null'
_.typeof( /someregexp/ );				// 'regexp'
// there is much more! see below.

Force!

Force some value to be of some type. A replacement value can be given in case value is invalid, without replacement a default literal of the forced type will be returned.

var left= '500px';
var callback= null;
// now some 10 lines of code to be save:
if ( typeof left === 'string' ){
		left= parseInt( left, 10 );
}
if ( left !== left || typeof left !== 'number' )
	left= 100;
}
if ( typeof callback !== 'function' ){
	callback= function(){}
}
callback( left );
// only 2 lines of code with force!
left=  _.forceNumber( left, 100 );
_.forceFunction( callback )( left );
// see below for more examples

Check it out, it's sweet! I've added force to types.js because I use it all the time and it seems to belong in here.

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For use with node.js you can install with npm install types.js

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Basic usage:

forceString Forces a value to be of a given type, and returns that value, a replacement, or it's literal default.

isString and notString (and the other is and not-types) are useful for single argument type checking.

allString (and the other all-types) are useful for checking if all given arguments are of a certain type.

hasString (and the other has-types) are useful for checking if one or more arguments are of a certain type.

typeof Returns a lowercase string representation of the type of the argument value, according to types.js type-definitions.

Be careful with using types.js for variables created with new Number() or other non-literal instantiations. No support for them, because I don't want to get 'number' on Types.typeof( new Number(10) ), as it actually is an object where you can add stuff to.

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some examples:

var _= Types;									// browser
var _= require( 'types.js' );					// in node.js with npm

var x;
// initialize a variable and be sure what type it will have in any case:
x= _.forceString();								// (empty String)
x= _.forceString( null, 'ok' );					// ok (as String)
x= _.forceString( null, [1, 2, 3] );			// (empty String)
x= _.forceString(33);							// 33 (as String)
x= _.forceNumber('35px');						// 35 (as Number)
x= _.forceNumber( true, function(){} );			// 0 (as Number)
x= _.forceBoolean('35px');						// false (as Boolean)

// initialize your object:
var Client= function( name ){
	this.name= _.forceString( name, 'no name given yet' );
};
var unborn= new Client();
console.log( unborn.name );						// 'no name given yet'

var func= null;
// call a function that might not exist anymore:
_.forceFunction( func )( 'some arguments', 'for func' );
// no crash, default empty function is called, returns undefined

// or add a replacement function in case the first one fails:
var message= _.forceFunction( func, function(args){
	return 'replacement function used '+ args;
 })( 'with some arguments' );
 console.log( message );
 // replacement function used with some arguments

// some default type checking:
x= _.isString( 'Hello types.js!' );				// true
x= _.isString( 23456 );							// false
x= _.isBoolean( false );						// true
x= _.isArray( [1,2,3] );						// true
x= _.isObject( [1,2,3] );						// false
x= _.isObject( /myRegExp/g );					// false
x= _.isNaN( parseInt('generate NaN') );			// true

x= _.notNull('');								// true
x= _.notUndefined( undefined );					// false
x= _.isDefined( null );							// true

// check multiple values in one call:
x= _.allString( '', " ", 'with text' );						// true
x= _.allString( '', ' ', 'with text', 123 );				// false
x= _.allStringOrNumber( '', ' ', 'with text', 123 );		// true
x= _.allObject( { key: 'nice' }, [], /regexp/ig );			// false
x= _.allArray( [1,2,3], [{}], new RegExp('stop') );			// false
x= _.allArray( [1,2,3], [{}], [false, true] );				// true

x= _.hasString( 123, { value: 'nice' }, ['?'] );			// false
x= _.hasStringOrNumber( [1,2], /reg/, 'true' )				// true
x= _.hasFunction( 123, { value: 'nice' }, function(){} );	// true
x= _.hasUndefined( 'render false!', 123, null );			// false
x= _.hasUndefined( 'render true!', 123, undefined );		// true

// check for a types.js type definition, returns lowercase string:
x= _.typeof( [1,2,3] );										// 'array'
x= _.typeof( null );										// 'null'
x= _.typeof( parseInt('generate NaN') );					// 'nan'
x= _.typeof( new Date() );									// 'date'
// etc..

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API

Types.parseIntBase

<Number> parseIntBase= 10

Holds the Radix used by forceNumber, defaults to decimals. Can be set to valid radixes for parseInt().

Types.forceBoolean

<String> Types.forceBoolean( value, replacement )

Returns value if value is of type Boolean. Otherwise it will try to convert value to be a Boolean. If that fails too, replacement will be tested for, or converted to, 'boolean' if possible. If that fails, the default types.js boolean literal is returned: a Boolean false

Types.forceString, Types.forceNumber, Types.forceArray, Types.forceObject

Just like forceBoolean, only applying the type denoted by the method name. See the force'Type' literals for the different methods below.

Types.forceFunction

<Function> Types.forceFunction( <Function> func, <Function> replacement )

Returns func if it is a Function. So you can call your function with Types.forceFunction(func)( args ). If it is a Function, it will call and pass the given arguments.

forceFunction will not try/catch func for other failures.

If func or replacement are not of type Function, a dummy function will be called returning undefined.

Types.typeof

<String> Types.typeof( value )

Returns a lowercase string representation of the type of value, according to types.js types. See all types.js type-definitions below.

Types.isBoolean

<Boolean> Types.isBoolean( value )

Returns true if the given argument is a Boolean true or false

Types.notBoolean

<Boolean> Types.isBoolean( value )

Returns true if the given argument is not a Boolean true or false

Types.hasBoolean

<Boolean> Types.hasBoolean( values, [value1, ..., valueN])

Returns true if any of the given arguments is a Boolean true or false

Types.allBoolean

<Boolean> Types.allBoolean( values, [value1, ..., valueN])

Returns true only if all given arguments are either a Boolean true or false

All remaining methods are equal to the last four above, except for that they differ in the type being checked. The complete list of all these methods:

not	is	has	all
notBoolean	isBoolean	hasBoolean	allBoolean
notString	isString	hasString	allString
notNumber	isNumber	hasNumber	allNumber
notStringOrNumber	isStringOrNumber	hasStringOrNumber	allStringOrNumber
notObject	isObject	hasObject	allObject
notArray	isArray	hasArray	allArray
notFunction	isFunction	hasFunction	allFunction
notRegexp	isRegexp	hasRegexp	allRegexp
notDate	isDate	hasDate	allDate
notNull	isNull	hasNull	allNull
notUndefined	isUndefined	hasUndefined	allUndefined
notDefined	isDefined	hasDefined	allDefined
notNaN	isNaN	hasNaN	allNaN

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types.js type definitions:

'boolean', 'string', 'number', 'object', 'array', 'function', 'regexp', 'date', 'null', 'undefined', 'nan', 'unknown'

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force'Type' method and default literals

format: <'Type'> force'Type'( <any type> value, <'Type'> replacement )

The literals returned by default:

forceBoolean	forceString	forceNumber	forceObject	forceArray	forceFunction
false	''	0	{}	[]	function(){}

change log

1.3.1

Added:

• change log in the readme, more convenient overview of changes.

• is/not/has/allDefined
  Now you can: if (_.isDefined(value) )
  instead of if (_.notUndefined(value) )