This is the slides for the YouTube video i did on this subject

1. JavaScript
Iterations
Charles Russell
Bennu Bird Media

2. Changes in Direction
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In the previous video we allowed our program to
change flow to one of many different program
blocks
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But that is not the only direction change we may
want. It is often desireable to repeatedly execute
the same block
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Looking for some value in a list
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Sending a group email
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In other words we want to loop

3. The While loop
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At the top of the loop the condition is checked
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If the condition is met then execute code block
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Loop will continue until condition not met.
while (conditional expression) {
//Do some stuff
}
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Be sure that eventually the condition will not be
met otherwise you get an infinite loop;

4. The Do loop
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At the bottom of the loop condition is checked
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Assures the code block will be executed at least
once
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Loop continues until condition false
do {
//code to execute goes here
} while (conditional expression);

5. Basic For loop
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Executes the loop a number of times
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Has three statements
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First excutes before the loop is executed
– Usually used for initialization
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Second conditional expression
– Code executes if true
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Third
– Executes after the code block before the next
iteration

6. Basic For Syntax
for (init ; conditional exp; prepForNext) {
//do some stuff
}

7. For looping through
properties
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Used to examine properties of an object
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Important to filter as all properties examined
even those inherited from parent and its
parent....
for (variable in Object) {
if ( Object.hasOwnProperty(variable) {
//code to execute
}
}

8. Cutting the loop
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break
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Halts code execution in the loop
– Stop further execution of code block and exit the
loop
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continue
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Halts execution of the rest of the code block
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Continues next iteration

9. Summary
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Iteration is another word for looping
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While loops check for conditional at the top of
the loop
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Be wary of the infinite loop
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Do loops check conditional at bottom of the loop
●
Basic for loops allow loops to be controlled by
number of executions
●
For in loops will check properties of Objects and
Arrays
●
Be sure to use hasOwnProperty method.

10. Next: Live Code