Global Libraries

Global library code is usually extremely simple.
A global “Hello, world” library might look like
this:

function createGreeting(s) {
  return "Hello, " + s;
}

// Web
window.createGreeting = function (s) {
  return "Hello, " + s;
};
// Node
global.createGreeting = function (s) {
  return "Hello, " + s;
};
// Potentially any runtime
globalThis.createGreeting = function (s) {
  return "Hello, " + s;
};

When looking at the code of a global library,
you’ll usually see:

• Top-level var statements or function declarations
• One or more assignments to window.someName
• Assumptions that DOM primitives like document or window exist