JavaScript Data Types and Objects
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Questions and Answers

What type of objects can contain properties and methods?

  • Strings
  • Symbols
  • Objects (correct)
  • Char codes
  • What is the range of values for a number in JavaScript?

  • 0 to 2,147,483,647
  • -2,147,483,648 to 2,147,483,647 (correct)
  • 0 to 1,000,000
  • -1,000,000 to 1,000,000
  • What is the purpose of the typeof operator?

  • To convert a value to a specific type
  • To give a string that describes the type of an expression (correct)
  • To check if a value is of a certain type
  • To create a prototype
  • 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.

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    Description

    This quiz covers JavaScript data types, including strings, objects, prototypes, and type conversions. It also includes information on accessing properties, the prototype chain, and the typeof operator.

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