“use strict”;

Tells the browser, please add some extra rules when you parse and try to execute my code.

The result is:
Object {}

With "use strict"; the result is:
Uncaught ReferenceError: perple is not defined

“use strict” says, you must declare a variable in order to use it. Which can be really helpful when you have mistyped errors, similarly spelled functions or objects and get squirrelly responses.

It can be used at the top of your file OR at the top of a function and must be on the first line.

What it does: (from Stack Overflow) –

  1. It catches some common coding bloopers, throwing exceptions.
  2. It prevents, or throws errors, when relatively “unsafe” actions are taken (such as gaining access to the global object).
  3. It disables features that are confusing or poorly thought out.

Peter Dillon

Development teams seek me out for visual design, reskinning, information hierarchy, usability, iconography, improving task flow, improving the front end build process and more. I specialize in creating engaging solutions to solve real world problems while designing beautiful applications that make the lives of users easier.