Comparison and logical operators & FOR and WHILE Loops

Comparison and logical operators

Comparison operators

You can evaluate a situation by comparing one value in the script to what you expect it might be. The result will be a Boolean: true or false.

1. ==
   • is equal to
   • this operator compares 2 values to see if they are the same
2. ===
   • strict equal to
   • this operator compares two values to check that both the data type and value are the same.
3. !=
   • is not equal to
   • this operator compares 2 values to see if they are not the same.
4. !==
   • strict not equal to
   • this operator compares 2 values to check that both he data type and value are not the same.
5. >
   • greater than
6. <
   • less than
7. >=
   • greater than or equal to
8. <=
   • less than or equal to

Logical operators

Comparison operators usually return single values of true or false. Logical operators allow you to compare the results of more than one comparison operator.

((5 < 2) && (2 >= 3))

1. &&
   • LOGICAL AND
   • if both expressions evaluate to true then the expression returns true. If just one of these returns false, the the expression will return false.
2. • LOGICAL OR
   • if either expression evaluates to true, then the expression returns true. If both return false, then the expression will return false.
3. !
   • LOGICAL NOT
   • this reverses the state of an expression. If it was false it would return true. If the statement was true. it would return false

     !true returns false; !false returns true;

Loops

Loops check a condition. If it returns true, a code block will run. Then the condition will be checked again and if it still returns true, the code block will run again. It repeats until the condition returns false. There are three common types of Loops:

FOR LOOPS

- If you need to run code a specific number of times, use a for loop. In a for loop, the condition is usually a counter which is used to tell how many times the loop should run.

for (var i = 0; i < 10; i++) {
    document.write(i);
    
}

WHILE LOOPS

- The purpose of a while loop is to execute a statement or code block repeatedly as long as an expression is true. Once the expression becomes false, the loop terminates.

var count = 0;
 document.write("Starting Loop ");
         
while (count < 10) {
    document.write("Current Count : " + count + "<br />");
    count++;
}

<== Back to ReadMe