Comments about Eloquent JavaScript: chapters 2 and 3

1. Javascript
Tricky stuff
Eloquent JavaScript - Chapters 2 and 3

2. Variables comparison
• null == undefined
• false == 0
• “” == 0
• “5” == 5
• Use === or !==

3. Boolean expressions
• 0, “”, null, undefined, NaN equiv. to false
• anything else equiv. to true

4. Automatic type
conversion
• “patata”+5
• null + “torious”
• “4” * 4 --> Number(“4”) * 4
• 4 * “patata”
• typeof NaN ?
• https://www.destroyallsoftware.com/talks/
wat

5. NaN
• NaN == NaN ?
• isNaN
• isNaN(“3”) ?

6. && ||
• var output = (input || “is input is false”)
• var output = (input && “input is true”)
• Evaluates the first part of the expression,
the second part only if necessary

7. Scope of variables
• Global
• Local
• var name OR name
• Closure
•

8. Efficiency
• Recursion vs loops

9. Functions
• Anonymous
• Arguments variable