reading-notes

Reading notes for Code Fellows!

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Operators and Loops

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Operators

Two types of operators are comparison operators and logical operators. Comparison operators evaluate a situation and return Boolean values of either true or false.

Comparison Operators

• == - is equal to
• != - is NOT equal to
• === - strict equal to
• !== - strict NOT equal to
• > - greater than
• < - less than
• >= - greater than or equal to
• <= - less than or equal to

Logical operators compare the results of more than one comparison operator, also returning a Boolean value.

Logical Operators

• && - Logical AND
• || - Logical OR
• ! - Logical NOT

Loops

Loops are programming tools that check for a condition and run a specified block of code if the condition returns true. After executing the block of code, the loop checks the condition again and continues to repeat the block of code intil a check returns false. Then the loop is exited.

There are three common types of loops:

• for - used when we need to run the code a specific number of times. In a for loop, the condition is typically a “counter”.
• while - used when we don’t know how many times the code should run. The condition can be something other than a counter.
• do while - similar in all respects to the while loop save for one key difference. The do while loop will always execute its code at least once.

For Loop Counters

The for lopp uses a counter as a condition to instruct the code to run a specified number of times. The counter of a for loop consists of three parts: initialization, condition and update and is contained in the parenthesis following the for keyword. Here is an example of a for loop set up:

for (var i = 0; i < 10; i++) {
  // Code goes here
}

• var i = 0 - initialization the variable i is created only one time when the for loop is first run.
• i < 10 - condition the loop should continue to run until it reaches the specified number.
• i++ - update every time the loop completes the block of code it increments the counter.

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