typeof-arguments

Description

typeof-arguments is a module that validates arguments' types passed to the enclosing function.

• Any bugs found? Give me to know on [e-mail]
• Also check out of-type package that checks whether the given value is of particular type (typeof-arguments is based on of-type package).

Installation

npm install typeof-arguments

var args = require('typeof-arguments');

Usage

args(arguments,types[,callback])

arguments [Object]

• It should always indicate the enclosing function arguments object

types [Array] of [String|RegExp] items.

• It should contain the list of expected types for each (or chosen) enclosing function parameter. The types[2] specifies the expected type(s) of arguments[2], etc.
• Possible values: 'null', 'undefined', or any value equal to constructor.name, eg. 'string', 'number', 'regexp', 'array', 'object', 'boolean','buffer', etc.
• The types [String] is case insensitive: 'String', 'string', 'StRiNg' checks if the arguments item is of type [String]. For types [RegExp] case insensitivity use i flag, eg.: /String/, /string/i, /sTrInG/i
• The types [String] can contain multiple allowed types, separated with |, eg: 'array|object', 'boolean|number|null|undefined', string|number. For types [RegExp] multiple values use (x|y) expression, eg: /(string|number)/i

Extra types:

• The types can contain the value: 'arguments'. It returns true for the arguments Object
• The types can contain the value: 'truthy'. It returns true for the arguments item's values like: "abc", true, 1, {}, [],function(){}, etc.
• The types can contain the value: 'falsy'. It returns true for the arguments item's values like: "", false, 0, null, undefined, etc.
• The types can contain the value: '' or 'any', then it returns true for the arguments item of any type. Use it if you do not want to check the type of the particular arguments item, eg. ['string','any','object|array']

var args = require('typeof-arguments');

hello('hello', "world!");

function hello(paramA,paramB){
  args(arguments,['string','string']);
}

callback [Function] (optional)

• if not passed, the TypeError with default message will be printed to the console, if the argument passed to the function is invalid.
• The TypeError default message is eg.:
  • Invalid argument [0]. The [String] argument has been passed, while the [Number] one is expected.
  • Invalid argument [2]. The [undefined] argument has been passed, while the argument of the type matching the regular expression: /array|object/i is expected.
  • Invalid argument [1]. The [Number] <<truthy>> argument has been passed, while the [falsy|String] one is expected.
• if passed, the default error message will not be printed to the console and the user can decide what to do inside the callback function
• the callback function is executed only if at least one argument passed through the enclosing function is of invalid type.
• the parameter actual [String] and expected [String] is passed through the callback function. The parameter actual indicates the actual type of the argument passed through the enclosing function, eg. '[String]', when the expected parameter indicates the type(s) expected by the user, eg. '[Array]', '[Boolean|Number]', /array|object/i.

var args = require('typeof-arguments');

hello(10, "hello!");

function hello(paramA,paramB){
  args(arguments,['any','string|number'],(actual,expected)=>{
    console.log(new Error(`Not good! You passed ${actual}, when you should have passed ${expected}.`));
  });
}

Return value

The function args() returns true when all arguments passed through the enclosing function are of valid types.

The function args() returns false when at least one of the arguments passed through the enclosing function is of invalid type.

var args = require('typeof-arguments');

hello("hello","world!");

function hello(paramA,paramB){
  var areValid = args(arguments,['string','string']);
  if(!areValid) return; //stop executing code if at least one argument is of invalid type
  return paramA + " " + paramB;
}

Samples

var args = require('typeof-arguments');

function hello(paramA,paramB,paramC){
  args(arguments,['number|string','any','null|array']);
}

hello("hello", "it's me!", null);
//no errors

hello(10, 20, [1,2,3]);
//no errors

hello(true,20,null);
//Invalid argument [0]. The [Boolean] argument has been passed, while the [Number|String] one is expected.

hello({name:'Paul'},false,/test/);
//Invalid argument [0]. The [Object] argument has been passed, while the [Number|String] one is expected.
//Invalid argument [2]. The [RegExp] argument has been passed, while the [null|Array] one is expected.

hello(10,20,null,30,40,50,60,70);
//no errors

hello(10);
//Invalid argument [2]. The [undefined] argument has been passed, while the [null|Array] one is expected.

more samples

var args = require('typeof-arguments');

function hello(paramA,paramB){
  args(arguments,['truthy|string',/(regexp|falsy)/i]);
}

hello();
//Invalid argument [0]. The [undefined] <<falsy>> argument has been passed, while the [truthy|String] one is expected.

hello('','');
//Invalid argument [0]. The [String] <<falsy>> argument has been passed, while the [truthy|String] one is expected.

hello(1,0);
//no errors

hello(0,1);
//Invalid argument [0]. The [Number] <<falsy>> argument has been passed, while the [truthy|String] one is expected.
//Invalid argument [1]. The [Number] <<truthy>> argument has been passed, while the argument of the type matching the regular expression: /(regexp|falsy)/i is expected.

hello([1,2,3],/test/);
//no errors

hello('hello',null);
//no errors

more samples

var args = require('typeof-arguments');

function hello(paramA,paramB,paramC){
  args(arguments,[/date|object|array/i,/^html.*element$/i,/^html(ul|li)element/i]);
}

var div = document.createElement('DIV');
var ul = document.createElement('UL');
var li = document.createElement('LI');
var a = document.createElement('A');

hello([1,2,3],null);
//Invalid argument [1]. The [null] argument has been passed, while the argument of the type matching the regular expression: /^html.*element$/i is expected.

hello([1,2,3],div,ol);
//no errors

hello([1,2,3],div,ul);
//no errors

hello(new Date(),a,div);
//Invalid argument [2]. The [HTMLDivElement] argument has been passed, while the argument of the type matching the regular expression: /^html[uo]listelement/i is expected.

more samples

var args = require('typeof-arguments');

function hello(paramA,paramB){
  args(arguments,['arguments|falsy',/((syntax|type)error)|falsy/i]);
}

function returnArguments(){
  return arguments;
}

hello(null,new TypeError());
//no errors

hello(false,new SyntaxError());
//no errors

hello(0,new Error());
//Invalid argument [1]. The [Error] argument has been passed, while the argument of the type matching the regular expression: /((syntax|type)error)|boolean/i is expected.

hello(1,false);
//Invalid argument [0]. The [Number] <<truthy>> argument has been passed, while the [arguments|falsy] one is expected.

hello(returnArguments,new TypeError());
//Invalid argument [0]. The [Function] <<truthy>> argument has been passed, while the [arguments|falsy] one is expected.

hello(returnArguments(),new TypeError());
//no errors