Runtime Type Checker in JS

README.md

Runtime Type checker in JS.

is(String, "foo") // true
is(/foo/, "foo") // true
is("foo", "foo") // true

// See test file for more exemples...

// Objects
var Address = {
  number: Number,
  street: String,
  city: String,
  zip: Number
}

var Email = /(.+)@(.+){2,}\.(.+){2,}/;

var Person = {
  name: String,
  age: Number,
  credentials: "granted",
  level: 1000,
  birthday: Date,
  human: Boolean,
  address: Address,
  emails: [Email]
}

is(Person, {
  name: "foo",
  age: 42,
  credentials: "granted",
  level: 1000,
  human: true,
  birthday: new Date(1985,10,12),
  address: {
    number: 42,
    street: "foo",
    city: "foo",
    zip: 42
  },
  emails: ["[email protected]"]
}) // should return true

checkType.js

function is(type, value) {
  var typeoftype  = typeof type;
  var typeofvalue = typeof value;
  if      (type === null)    return value != undefined;
  else if (typeoftype == "string")   return type === value;
  else if (typeoftype == "number")   return type === value;
  else if (typeoftype == "boolean")  return type === value;
  else if (typeoftype == "function") return (typeofvalue === typeof type() || value instanceof type);
  else if (type instanceof Array) {
    if (!(value instanceof Array)) return false;
    if (type.length == 1 && value.length >= 0) {
      for (var i in value){
        if (!is(type[0], value[i])) return false;
      }
    }
    return true;
  }
  else if (type instanceof RegExp) {
    if (!(typeoftype != "string")) return false;
    return type.test(value);
  }
  else if (typeoftype == "object") {
    if (!value) return false;
    for (var i in type){
      if (!is(type[i], value[i])) return false;
    }
    return true;
  }
}

test-checkType.js

function should(type, value){
  if (!is(type, value)) console.error("KO", value)
  else console.log("OK")
}
function shount(type, value){
  if (is(type, value)) console.error("KO", value)
  else console.log("OK")
}

// String
should(String, "")
should(String, "foo")
should("foo", "foo")
should(/foo/, "foo")
shount(String, false)
shount(String, 1)
shount(String, [])
shount(String, {})
shount(String, String)
shount("foo", "bar")
shount(/foo/, "bar")

// Number
should(Number, 42)
should(42, 42)
shount(Number, "")
shount(Number, "foo")
shount(Number, false)
shount(Number, [])
shount(Number, {})
shount(Number, Number)
shount(42, 2)

// Number
should(Boolean, true)
should(Boolean, false)
should(true, true)
should(false, false)
shount(Boolean, "")
shount(Boolean, "foo")
shount(Boolean, [])
shount(Boolean, {})
shount(Boolean, Number)
shount(true, false)

// Array
should(Array, [])
should([], [])
should([], ["foo", "bar"])
should(Array, ["foo", "bar"])
should([String], ["foo", "bar"])
should(["foo"], ["foo"])
shount([Number], ["foo", "bar"])
shount([Boolean], ["foo", [], 4])


// Date
should(Date, new Date(1985,10,12))

// Objects
var Address = {
  number: Number,
  street: String,
  city: String,
  zip: Number
}

var Email = /(.+)@(.+){2,}\.(.+){2,}/;

var Person = {
  name: String,
  age: Number,
  credentials: "granted",
  level: 1000,
  birthday: Date,
  human: Boolean,
  address: Address,
  emails: [Email]
}

should(Person, {
  name: "foo",
  age: 42,
  credentials: "granted",
  level: 1000,
  human: true,
  birthday: new Date(1985,10,12),
  address: {
    number: 42,
    street: "foo",
    city: "foo",
    zip: 42
  },
  emails: ["[email protected]"]
})

shount(Person, {
  name: String,
  age: Number,
  credentials: "granted",
  level: 1000,
  human: Boolean,
  address: {
    number: Number,
    street: String,
    city: String,
    zip: Number
  },
  emails: [String]
})