JavaScript Data Types and Objects

Study Notes

In JavaScript, a string is a sequence of characters enclosed in quotes, apostrophes, or backticks.
Characters are just named symbols, and there can be more than one character with the same name.
Strings can be concatenated, joined, trimmed, split, and interpolated.
Internally, strings are not exactly strings of characters, but they feel like they are.
To understand strings, we have to go a bit deeper and ask: What is a character?
A JavaScript string is a sequence of code units, also known as char codes.
A symbol is a unique thing that gets created every time it is created.
A string can have a description, but it is not good for anything else other than printing.
Objects are a special type of string that can contain properties and methods.
An object is a collection of named properties and values.
You can access properties with square-bracket notation.
Values of non-objects are “stored directly” while the values of objects are the pointers, not the objects themselves.
Every object in JavaScript has a prototype.
When looking up properties, the prototype chain is searched.
Prototypes are very useful when creating a bunch of objects that look or behave similarly.
When you “unhook” an object from all of the variables that reference it, the object becomes garbage.
Other kinds of objects include functions and regular expressions.
JavaScript has a set type in its standard library.
The typeof operator can give you a string that tells you the type of an expression.
Values in a strongly typed language are always of a specific type.
Values in a weakly typed language can be of any type.
When a boolean is expected, a true or false value is used.
When a number is expected, an integer value between -2,147,483,648 and 2,147,483,647 is used.
When a string is expected, a string value between "a" and "z" is used.
To do a type conversion explicitly, use one of the methods listed above.