ECMAScript5 Features — Strict Mode, JSON And More

Joe Clark
Joe Clark
Jul 10, 2017 · 1 min read

Strict Mode is a new feature in ECMAScript 5 that allows you to place a program, or a function, in a “strict” operating context. This strict context prevents certain actions from being taken and throws more exceptions (generally providing the user with more information and a tapered-down coding experience).

Since ECMAScript 5 is backwards-compatible with ECMAScript 3, all the “features” that were in ECMAScript 3 that were “deprecated” are just disabled (or throw errors) in strict mode, instead.

Strict mode helps out in a couple ways:

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

For more details: Software Tool Video

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