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cparks-javascript
beginning javascript vocabulary
| Term | Definition |
|---|---|
| Array Literals | List values in a pair of square brackets |
| Accessing array elements | 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 | 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 | Syntax. True-False |
| Boolean logical operators | returns true if both the expressions evaluate to true. |
| Comparison operators | An important thing to note here is that not only Boolean literals (true and false) assert truth or false , but there are some other ways too to derive true or false.Have a look at the examples. |
| Definition | 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. Comments are like notes , suggestions , warnings ,etc. |
| Single line comment | Anything on the line following // will be a comment while anything before will still be code. |
| Mutli-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.You give each timer a unique name, and may have up to 10,000 timers running on a given page. |
| 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.It is like a reusable piece of code. |
| Function calling | functionName(argument1, argument2, ..., argumentN); |
| Function hoisting | The two ways of declaring functions produce different results. 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. |
| Pl | 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. |
| 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, other than the acknowledgement of the message. |
| 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. |
| 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, and the index of the last character in a string called stringName is stringName.length - 1. |
| 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. Checks a value against a list of cases, and executes the first case that is true. |
| Variable assignment | var name = value; |
| Variable changing | varname = newValue |
Created by:
2014parksc
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