Podcast
Questions and Answers
What type of objects can contain properties and methods?
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?
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?
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
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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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