May 2018
Intermediate to advanced
376 pages
9h 22m
English
Content preview from Get Programming with JavaScript Next
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Lesson 13. Symbol—a new primitive
After reading lesson 13, you will
- Know how to use symbols as constants
- Know how to use symbols as object keys
- Know how to create behavior hooks with global symbols
- Know how to modify object behavior with well-known symbols
In JavaScript there are objects and there are primitives. The primitives of JavaScript are strings, numbers, Booleans (true or false), null, and undefined. Symbol is a new primitive added in ES2015 and is the first primitive added to JavaScript since its creation. A symbol is a unique value that’s used for hooking into the behavior of built-in JavaScript objects. Symbols can be broken into three categories:
- Unique symbols
- Global symbols
- Well-known symbols
Consider this
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