Type Checking

example.js

var is={};
(function(t,c,i,e,o){c=function(o){return function(v){return o==v.constructor;}};t=t.split(",");i=0;while(e=t[i++])this[e]=c(eval(e))})
.call(is, "String,Array,Object,Function,Number");

console.log( is.String( "123" ) ); // true
console.log( is.String( 123 ) ); // false
console.log( is.Number( 123) ); // true
console.log( is.Object( {} ) ); // true

index.js

(function(t,c,i,e,o){c=function(o){return function(v){return o==v.constructor;}};t=t.split(",");i=0;while(e=t[i++])this[e]=c(eval(e))})

package.json

{
  "name": "typechecking",
  "keywords": [ "check", "type", "checktype" ]
}