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mcrosby-JavaScript
Beginning JavaScript Vocabulary
| Term | Definition |
|---|---|
| Array literals | The most common of which is to list values in a pair of square brackets |
| Accessing array elements | indexes start at 0 and increment by 1, so the first element's index is 0, the second element's index is 1, the third element's is 2, etc. |
| Multi-dimensional Arrays | A two-dimensional array is an array within an array. If you fill this array with another array you get a three-dimensional array and so on. |
| Array constructor | create an array |
| Accessing nested array elements | Accessing multi dimensional array elements is quite similar to one-dimension arrays . They are accessed by using [index][index] |
| Boolean literals | true or false syntax |
| Boolean logical operators | expression1 && expression2 //returns true if both the expressions evaluate to true expression3 || expression4 // return true if either one of the expression evaluates to true |
| Comparison operators | x === y // returns true if two things are equal x !== y // returns true if two things are not equal x <= y // returns true if x is less than or equal to y x >= y // returns true if x is greater than or equal to y x < y // returns true if x is less tha |
| note | Boolean literals (true and false) assert truth or false |
| == vs. === | does just value checking ( no type checking ) , whereas , === does both value checking and type checking |
| Definition | Comments are like notes , suggestions , warnings ,etc. that you can put for yourself. Code comments are not executed |
| Single Line Comment | Anything on the line following // will be a comment while anything before will still be code. |
| Multi-Line Comment | Anything between /* and */ will be a comment. |
| console.log | Prints text to the console. Useful for debugging. |
| console.time | This function starts a timer which is useful for tracking how long an operation takes to happen |
| console.timeEnd | stops a timer that was previously started by calling console.time() |
| Function definition | To use a function, you must define it somewhere in the scope from which you wish to call it. A function definition (also called a function declaration) consists of the function keyword, |
| Function calling | functionName(Argument1,2,... |
| Function hoisting | Declaring a function one way "hoists" it to the top of the call, and makes it available before it's actually defined. |
| if | It simply states that if this condition is true , do this , else do something else ( or nothing ) . It occurs in varied forms. |
| else | A fallback to an if statement. This will only get executed if the previous statement did not. |
| else if | This is like an else statement, but with its own condition. It will only run if its condition is true, and the previous statement's condition was false. |
| For Loops | You use for loops, if you know how often you'll loop. The most often used varName in loops is "i". |
| While Loops | You use while loops, if you don't know how often you'll loop. |
| Do while loops | You use do while loops, if you have to loop at least once, but if you don't know how often. |
| random | Returns a random number between 0 and 1 |
| floor | Returns the largest integer less than or equal to a number. |
| pow | Returns base raised to exponent. |
| ceil | Returns the smallest integer greater than or equal to a number. |
| PI | Returns the ratio of the circumference of a circle to its diameter, approximately 3.14159 or in better terms, the value of PI |
| sqrt | Returns the square root of a number. |
| % (Modulus) | it returns the remainder left after dividing the left hand side with the right hand side. |
| isNaN | Returns true if the given number is not a number , else returns false. |
| Basic Arithmetic | Doing basic arithmetic is simple. basic math |
| Prefix and Postfix increment/decrement operators | Prefix increment / decrement operators are operators that first increase the value of the variable by 1 (increment) or decrease the value of an expression / variable by 1 (decrement) and then return this incremented / decremented value |
| Object Literals | "property 1": value1, property2: value2, number: value3 |
| Property Access | name1[string] name2.identifier |
| Classes | A class can be thought of as a template to create many objects with similar qualities. Classes are a fundamental component of object-oriented programming (OOP). |
| Alert | Display an alert dialog with the specified message and an OK button. Note: The alert dialog should be used for messages which do not require any response on the part of the user, |
| Confirm | returns true if confirmed false otherwise |
| Prompt | The prompt() displays a dialog with an optional message prompting the user to input some text. If the user clicks the "Cancel" button , null is returned. |
| Strings | Strings are text. They are denoted by surrounding text with either single or double quotes. |
| Concatenation | string1+string2 |
| Length | Returns the length of the string. |
| toUpperCase, toLowerCase | Changes the cases of all the alphabetical letters in the string. |
| trim() | Removes whitespace from both ends of the string. |
| replace() | Returns a string with the first match substring replaced with a new substring. |
| charAt() | Returns the specified character from a string. Characters in a string are indexed from left to right. The index of the first character is 0 |
| substring() | Returns the sequence of characters between two indices within a string. |
| indexOf | Returns the index within the calling String object of the first occurrence of the specified value, starting the search at fromIndex, Returns -1 if the value is not found. The indexOf method is case sensitive. |
| switch | Checks a value against a list of cases, and executes the first case that is true. |
| Ternary Operator | The ternary operator is usually used as a shortcut for the if statement. |
| Variable Assignment | var name = value; |
| Variable changing | varname=newValue |
Created by:
2015crosbym
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