types.js

types.js

A tiny (1.8kb), 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.

A few quick examples with types.js:

_.typeof( [] );							// 'array'
_.typeof( null );						// 'null'
_.typeof( /someregexp/ );				// 'regexp'
_.typeof( parseInt('Not A Number!') );	// 'nan'
_.forceString( 123 );					// '123'
_.allDefined( 'good', false, null );	// true (null !== undefined in strict mode)
_.hasObject( 'not', 'really' );			// false
// 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 );
}
// check if parseInt returned NaN..
if ( left !== left || typeof left !== 'number' )
	left= 100;
}
if ( typeof callback !== 'function' ){
	callback= function(){}
}
callback( left );
// 2 lines of code with force, and a better read if you ask me:
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:

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

is'Type' and not'Type' are useful for single argument type checking.

all'Type' is useful for checking if all given arguments are of a certain type.

has'Type' is 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.

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some more 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)
x= _.forceArray("you'll get an array");			// []

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

// some default type checking:
x= _.isDefined()								// false
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(). Note that once set, all following forceNumber calls will use the new Radix.

_.parseIntBase= 0xf;
// parse from hexadecimal
var nr= _.forceNumber( 'a linefeed' );
console.log( nr );
// 10 (decimal)

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

var assert= _.forceBoolean( 'Only a true true returns true' );
console.log( assert );
var assert= _.forceBoolean( NaN != NaN );
console.log( assert );
// true

Types.forceString, 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.forceNumber

<Number> forceNumber( <String>/<Number> value, <String>/<Number> replacement )

Returns value if it is a Number or convertable to a Number. Returns replacement if value is invalid or not convertable. Returns a Number object with a .void property set to true if no valid value and replacement were given or no conversion was possible.

You can check yourNumber.void to see if yourNumber is set to a valid number. If .void is true, yourNumber is not set to a number, but to a Number object which is ready for mathemetical operation, and defaults to 0.

Types.typeof( Types.forceNumber() ); returns 'number', as it is a Number and you can use it as number.

Example: make a numberFilter for arguments with the new forceNumber:

function numberFilter(){
	var numbers= [];
	for( var arg in arguments ){
		var value= _.forceNumber( arguments[arg] );
		if( value.void )
			continue;
		numbers.push( value );
	}
	return numbers;
}

function someFunc(){
	return numberFilter.apply( this, arguments );
}
console.log( someFunc('ignore', 1, 'the', 2, 'strings!', 3) );
// [ 1, 2, 3 ]
console.log( someFunc('1 but', '2 not', '3 unconditional!') );
// [ 1, 2, 3 ]

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.

var showAuthor= function( name ){
	console.log( 'Author: '+ _.forceString(name) );
};

_.forceFunction( showAuthor )( 'Dennis Raymondo' );
// Author: Dennis Raymondo

var showAuthor= null;
// now call with an anonymus replacement function as showAuthor will fail:
_.forceFunction( showAuthor, function(name){
	console.log( 'Could not call showAuthor! Arguments: '+ _.forceString(name) );
})( 'Dennis Raymondo' );
// Could not call showAuthor! Arguments: Dennis Raymondo

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.

var nan= parseInt( 'damn NaN!' );
console.log( _.typeof(nan) );
// 'nan'

Types.isBoolean

<Boolean> Types.isBoolean( value )

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

console.log( _.isBoolean(false) );
// true

Types.notBoolean

<Boolean> Types.isBoolean( value )

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

console.log( _.notBoolean('not a Boolean') );
// true

Types.hasBoolean

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

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

console.log( _.hasBoolean('the third', null, false) );
// true

Types.allBoolean

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

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

console.log( _.allBoolean(false, null, true) );
// 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'

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force'Type' method and default literals

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

The literals returned by default:

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

change log

1.3.9

Removed 'unknown' from types.js type definitions. It was meant to be like a final state, for if no other matching type could be found, but in the codebase as it is now, that state can never be reached.. If Javascript ever invents a brand new type, types.js will return 'defined' on that one if I would not take action and implement support for it.

Updated the readme.

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1.3.5

Changed:

• forceNumber doesn't return 0 by default anymore. It now returns a Number object with a .void property which is set to true if no valid Number was given or no conversion was possible.

  Just use: _.forceNumber( value, 0 ); to return a 0 as replacement, it only is not default anymore.

  I made this change because I wanted to be able to check if forceNumber was successful. Just a 0 can be very misleading and a source for bugs. NaN is a failure IMO, so I made a kind of replacement feature in forceNumber.

  You can now check for yourNumber.void to see if it is set. If .void is true, yourNumber is a Number object which is ready for mathemetical operation, and defaults to 0, this in contrast with NaN, which is almost totally unusable.

  example:

  // generate a void Number:
  var nr= forceNumber();
  console.log( nr.void );
  // true
  // don't do the following after a forceNumber without a valid replacement:
  console.log( nr );
  // { void: true }
  // instead do what cannot be done with NaN:
  console.log( 0 + nr );
  // 0
  // or check before usage:
  ( nr.void )
  	? console.log( 'void?', nr+= 36/ 4 );
  	: console.log( nr );
  // void? 9
  etc..
  

Updated:

• Jasmine tests for forceNumber and isDefined
• speed optimization for isObject

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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) )