Beginning JavaScript Vocab
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| Array literals | You can create arrays in two different ways. 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
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| 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.
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| Accessing array elements | You can get elements out of arrays if you know their index. 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.
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| Array constructor | You can also create an array using the Array constructor.
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| Accessing nested array elements | Accessing multi dimensional array elements is quite similar to one-dimension arrays . They are accessed by using [index][index]..... (number of them depends upon the number of arrays deep you want to go inside).
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| Boolean literals | Syntax
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| Boolean logical operators | These operators have the following meanings, where x and y represent values of TRUE or FALSE.
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| 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
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| 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. Comments are like notes , suggestions , warnings ,etc.
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| Multi-Line Comment | Anything between /* and */ will be a comment
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| console.log | Prints text to the console. Useful for debugging.
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| 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.When you call console.timeEnd() with the same name.
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| console.timeEnd | Stops a timer that was previously started by calling console.time().
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| Function definition | A function is a JavaScript procedure—a set of statements that performs a task or calculates a value
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| 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.
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| if statement | It simply states that if this condition is true , do this , else do something else ( or nothing ) . It occurs in varied forms.
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| else | A fallback to an if statement. This will only get executed if the previous statement did not.
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| 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.
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| For Loops | You use for loops, if you know how often you'll loop. The most often used varName in loops is "i".
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| While Loops | You use while loops, if you don't know how often you'll loop.
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| Do While Loops | You use do while loops, if you have to loop at least once, but if you don't know how often.
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| random | Returns a random number between 0 and 1
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| floor | Returns the largest integer less than or equal to a number.
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| pow | Returns base raised to exponent.
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| ceil | Returns the smallest integer greater than or equal to a number.
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| 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.
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| sqrt | Returns the square root of a number.
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| % (Modulus) | it returns the remainder left after dividing the left hand side with the right hand side.
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| isNaN | Returns true if the given number is not a number , else returns false.
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| Basic Arithmetic | 4 + 5; // 9
4 * 5; // 20
5 - 4; // 1
20 / 5; // 4
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| 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.
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| Object Literals | var obj = {
name: "Bob",
married: true,
"mother's name": "Alice",
"year of birth": 1987,
getAge: function () {
return 2012 - obj["year of birth"];
},
1: 'one'
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| Property Access | obj['name']; // 'Bob'
obj.name; // 'Bob'
obj.getAge(); // 24
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| 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).
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| 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.
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| confirm | if ( confirm("Are you sure you want to delete this post?") ) {
deletePost();
}
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| 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.
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| Strings | Strings are text. They are denoted by surrounding text with either single or double quotes.
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| Concatenation | "some" + "text"; // returns "sometext"
var first = "my";
var second = "string";
var union = first + second; // union variable has the string "mystring"
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| length | Returns the length of the string.
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| toUpperCase, toLowerCase | Changes the cases of all the alphabetical letters in the string.
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| trim() | Removes whitespace from both ends of the string.
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| replace() | Returns a string with the first match substring replaced with a new substring
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| charAt() | Returns the specified character from a string. Characters in a string are indexed from left to right.
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| substring() | Returns the sequence of characters between two indices within a string.
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| 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.
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| 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.
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| Ternary Operator | The ternary operator is usually used as a shortcut for the if statement.
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| Variable Assignment | var name = value;
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| Variable changing | varname = newValue
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To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
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