Learning Javascript From Mr Saem

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HTML CSS JavaScript 5

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First Script 10

Add Javascript to it 11

Script Position 12

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Should end with 14

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Not to use In-Line Script 17

CSS at the Top Scripts at the bottom 18

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Variables 25

We create variable to hold some data. So variable is a container. That works as a little piece of computer memory. 26

These need to be in the lowercase. The name of the variable is up to us. No spaces are allowed while naming these. These could be letters, Numbers, _ or $ But you cannot start with a number 27

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You may split the variables into one line aswell 31

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You may use “ “ or ‘ ’. But do not mix them such as “ ‘ Javascript understands the data type on its own by the way we assign it. It will understand boolean /logic when we define it as true/false 34

We need to ask questions so we shall use IF for that 35

You will always find these in pairs if you have an opening one you will find A closing one as well. Even if it is after many multiple lines. But it needs to be there 36

A All conditions should boil down into TRUE or FALSE TRUE FALSE 37

oth 38 So both are not =

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Not equal to 41

Code Block 42

var amount = 500; if ( amount < 1000 ) { alert ("Its less than 1000"); } 43

Using else 44

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47 = is a command. NOT a polite description We are setting a value We are assigning a value

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Some operators are considered more important than others eg Particularlay * and / are regarded more important than others. 49

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IF you are checking values are equal use the == operator 51

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53 You are telling You are asking Exactly equal

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55 AND OR

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var a=15; alert(++a); 59 What should the output be?

var a=15; alert(a++); 60 What should the output be?

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Loops 63

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var a=1; while (a<10) { alert(a); } 66 Infinite Loop Created While Loop

var a=1; while (a<10) { alert(a); a++; } 67 While Loop (Output)

var a=100; while (a<10) { alert(a); a++; } 68 While Loop (Output).What should it be ?

Do While. The output ? var a=100; do { alert(a); a++; } while (a<10); 69

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A short hand way 71

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The for loop 73 OUTPUT

Three Parts of Four Loop 74 VARIABLE DECLARATION - The first part of the loop which initializes the variable at the beginning of the loop to some value. This value is the starting point of the loop. INCREMENT STATEMENT - The increment statement is the third part of the loop. It is the part of the loop that changes the value of the variable created in the variable declaration part of the loop. The increment statement is the part of the loop which will eventually stop the loop from running. CONDITION - The second part of the loop, and it is the part that decides whether the loop will continue running or not. While the condition in the loop is TRUE, it will continue running. Once the condition becomes FALSE, the loop will stop.

The while loop The code within a while loop will execute while the specified condition is true. 75

In the above code, a variable named num is initialized with the value of 0. The condition in the while loop is that while num is less than 25, 5 should be added to num. Once the value of num is greater than 25, the loop will stop executing The while loop

The do-while loop The do-while loop is very similar to the while loop, but it does things in reverse order. The mechanism of the while loop is - while a condition is true, perform a certain action. The mechanism of the do-while loop is - perform a certain action while a condition is true. Furthermore, the code within a do-while loop will always execute at least once, even if the specified condition is false. This is because the code is executed before the condition is tested. 77

Syntax: do{ execute this code; } while (condition); In the above code, a variable named num is initialized with the value of 5. The condition in the do-while loop is that while num is less than 25, 5 should be added to num. Once the value of num is greater than 25, the loop will stop executing The do-while loop

Breaking out of a loop You can completely break out of a loop when it is still running. This is achieved with the break keyword. Once a loop is exited, the first statement right after it will be executed. The break keyword provides an easy way to exit a loop if an error occurs, or if you found what you were looking for 79

In the above example, the for loop is set to iterate 9 times and print the current value of the variable a during each iteration. The if statement within the loop states that when the variable a is equal to 5, break out of the loop Breaking out of a loop

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