README.md

typsy

Simple, chainable runtime type-checking for JavaScript

install

npm install --save typsy

import

// myfile.js
// ES module
import { typeCheck } from "typsy";

// Node.js
const typeCheck = require("typsy").typeCheck;

use

const x = "This is a string";

typeCheck(x).isString().yields(); // true

typeCheck(x).isInteger().yields(); // false

typeCheck(x).isString().or().isInteger().yields(); // true

the almighty yields

yields() returns whether the check is true or not. It must be called at the end to return true or false

checks

isTrue();
isFalse();
isInteger();
isString();
isEmptyString();
isAllWhiteSpace();
isBoolean();
isFloat();
isObject();
isNull();
isUndefined();
isArray();
isEmptyArray();
isFunction();
isDate();
isSet();
isWeakSet();
isMap();
isWeakMap();
isFloat();
isObject();
isEmptyObject();
isNaN();
isCollection();
isBigInt();
isSymbol();
isHTML();

methods

and();
or();
unless();

not modifier

pass any built-in check false

typeCheck(21).isArray(false).yields(); // returns true;

custom checks

Use the check function to insert a custom check function.

  function isNegative(value){
    return value < 0;
  }
  
  typeCheck(12).check(isNegative).yields(); // false
  typeCheck(-12).check(isNegative).yields(); // true
  

  typeCheck(12).isInteger().and().check(isNegative).yields(); // false
  typeCheck(-12).isInteger().and().check(isNegative).yields(); // true
  typeCheck(12).isInteger().or().check(isNegative).yields(); // true

yields callbacks

yields accepts a truth-handler and false-handler function respectively Both callbacks use the typeChecked value as its argument. This is especially useful for logging.

function myTrueCallback(){};

function myFalseCallback(){};

typeCheck(21).isInteger().yields(myTrueCallback, myFalseCallback); // returns true & myTrueCallback is fired
typeCheck("toot").isInteger().yields(myTrueCallback, myFalseCallback); // returns false & myFalseCallback is fired

with the yields callback you can even shorten your code:

// instead of 
if(typeCheck(21).isInteger().yields()){
  handleTrue(21);
} else {
  handleFalse(21)
}
// you can use this!
typeCheck(21).isInteger().yields(handleTrue, handleFalse);

neat recipes

myFunction(typeCheck(myVariable).isInteger().or().isString().yields()? myVariable : 1);