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dharlow-JavaScript
Beginning JavaScript Vocabulary
| Term | Definition |
|---|---|
| Array Literals | The most common of which is to list values in a pair of square brackets. JavaScript arrays can contain any types of values and they can be of mixed types. |
| Accessing Array Elements | You can get elements out of arrays if you know their index,indexes start at 0 and increment by 1 |
| Multi-Dimensional Arrays | The two-dimensional arrays are the arrays within arrays. If you fill this array with another array you get a three-dimensional array and so on and so forth |
| Array Constructor | You can also create an array using the Array constructor |
| Accessing nested array elements | They are accessed by using [index][index]..... (number of them depends upon the number of arrays deep you want to go inside). |
| Boolean Literals | true or false |
| 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 !expression5 // returns the opposite boolean value of the expression |
| 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 |
| Note | Not only Boolean literals (true and false) assert truth or false , but there are some other ways too to derive true or false. Such as,if(1)console.log("True!"); // output True! , since any non-zero number is considered to be true |
| == vs. === | A simple explanation would be that == does just value checking ( no type checking ) , whereas , === does both value checking and type checking |
| Code Comments | Code comments are used for increasing the readability of the code.If you write 100 lines of code and then forget what each function did , it's not useful at all |
| 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 commen |
| 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 | A function is a JavaScript procedure—a set of statements that performs a task or calculates a value |
| Function Calling | functionName(argument1, argument2, ..., argumentN); |
| 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 (π). Note in syntax , we do not put `()` at the end of `Math.PI` because `Math.PI` is not a function. |
| 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 |
| 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. |
| Confirm | confirm("message") //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 |
| Concatenation | Strings are text |
| 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. |
| chartAt() | Returns the specified character from a string. |
| 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 | Acts like a big if / else if / else chain. |
| 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:
2016harlowd
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