typeof-arguments

Description

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

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] items.

• It should contain the list of expected types for each (or chosen) enclosing function parameter.
• The item possible values: 'null', 'undefined', or any value equal to contructor.name, eg. 'string', 'number', 'regexp', 'array', 'object', 'boolean'.
• The upper and lower cases do not make any difference: 'String', 'string', 'StRiNg' checks if the argument is of type [String]
• The item value can equal to: '' or 'any', then the argument can be of any type
• The item can contain multiple allowed types, separated with |, eg: 'array|object', 'boolean|number|null|undefined', string|number

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. The [String] argument has been passed, while the [Number] 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 parameter actual [String] and expected [String] is passed to the callback function. The parameter actual indicates the actual type of the argument passed to the enclosing function, eg '[String]', when the expected parameter indicates the type(s) expected by the user, eg. '[Array]', '[Boolean|Number]'.

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 to the enclosing function are of valid types. The function args() returns false when at least one of the arguments passed to 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. The [Boolean] argument has been passed, while the [Number|String] one is expected.

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