is a shortcut to (typeof foo === 'undefined') || (foo === null)

Installation | Usage | Annotated source | License

npm install not-defined --save

This snippet of code

var notDefined = require('not-defined')

if (notDefined(foo)) {
  // do something, usually throw a TypeError
}

is equivalent to

if ((typeof foo === 'undefined') || (foo === null)) {
  // do something, usually throw a TypeError
}

You can also use a shorter but still semantic form like

var no = require('not-defined')

if (no(foo)) {
  // do something, usually throw a TypeError
}

• Type less.
• Better readability (even your boss will understand your code ^:).
• Can save bytes in your builds.
• Easier to autocomplete in editors.

This is my first npm package written using KISS Literate Programming. It is a very basic, plain ES5 function that is 73 characters long

module.exports=function(x){return (typeof x==='undefined')||(x === null)}

MIT