Syntax Basics
Operators, Control Structures
Variables
Reserved Words
JavaScript has a list of reserved identifiers. You cannot use these words for your identifiers - click on image to expand
Words You cannot use
Identifiers
An identifier must start with a letter, a dollar sign, or an underscore. After the first character, you may use letters, numbers, underscores, or dollar signs.
Identifiers
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Case Sensitive
Case Sensitive
Literals
A literal is a value that you directly represent in your program - as opposed to a variable.
Whitespace
Use whitespaces to format your code and improve readability.
vs 
Whitespaces are ignored in JavaScript.
Loading JavaScript Files
Loading JavaScript Files
Comments
Comments: Single Line & Multi Line
For single line, everything after // is ignored. In multi line, everything between /* and */ is ignored.
Comments
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HTML Comments
Comments
Line Terminators
JavaScript uses a semicolon to separate statements.
Automatic Semicolon Insertion
If you forget a semicolon, JavaScript will try to add a semicolon for you. This can be very dangerous. Always finish your statements with a semicolon.
Active Learning
Active Learning
Code output?
Line Break
For the return keyword, the break keyword, the continue keyword, and the throw keyword, a line break will be interpreted as a semicolon.
If ... Else
If ... Else
Comparison Operators
Take x=7 for the following comparisons.
| Operator | Description | Comparing | Returns |
|---|---|---|---|
| === | equal value/type | x === 7 | true |
| !== | not eq value or type | x !== 7 | false |
| > | greater than | x > 7 | false |
| < | less than | x < 7 | false |
| >= | greater or equal | x >= 7 | true |
| <= | less or equal | x <= 7 | true |
Comparison Operators
Take x=7 and y=5 for the following comparisons.
| Operator | Description | Comparing | Returns |
|---|---|---|---|
| && | and | (x < 10 && y > 1) | true |
| || | or | (x === 7 || y === 7) | true |
| ! | not | !(x === 7) | false |
Active Learning
Download images & starter code
click on zip image above
For Loops
Loops - Active Learning
For Loops
Lexical Conventions
Style Guide (reference)
JavaScript Reference
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference