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JavaScript Tutorial 4 -Decision Making with Control Structures and Statements
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Tutorial 4
Decision Making with Control Structures and Statements
Section A - Decision Making
JavaScript Tutorial 4 -Decision Making with Control Structures and Statements
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Tutorial 4A Topics
• Section A - Decision Making– if statements– if…else statements– Nested if statements– switch statements
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Decision Making
• Decision Making– Process of determining the order in
which statements execute in a program• AKA – flow control
– Decision-Making Structures• Special type of JavaScript statements used
for making decisions
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Decision Making
• if Statements– Used to execute specific programming code if
the evaluation of a conditional expression returns a value of true
• “Do this or don’t do this”
– Syntax (3 primary parts)
if (conditional_expression) {statement(s);
}
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Decision Making
• if Statements– Operation
• If the conditional expression is true, the statement(s) is/are executed
• Control then continues to subsequent code
– Command block• Multiple statements contained within a set
of braces (require curly braces)
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JavaScript Tutorial 4 -Decision Making with Control Structures and Statements
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JavaScript Tutorial 4 -Decision Making with Control Structures and Statements
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Decision Making
• if Statements– Conditional Expression
• Can consist of:– Comparison operators– Logical operators– Combination of the two
• Must resolve to Boolean value
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Decision Making
• if…else Statements– Used to execute one set of code if the evaluation
of a conditional expression returns a value of true, otherwise executes another set of code
• “Do this or do something else”
– Syntax
if (conditional_expression) {statement(s);
} else {statement(s);
}
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JavaScript Tutorial 4 -Decision Making with Control Structures and Statements
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Decision Making
• Nested if and if…else Statements– Nested statements
• Statements contained within other statements
– Syntax (variable)if (conditional_expression) {
statement(s);if
(conditional_expression) {
statement(s);}
} else {statement(s);
}
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JavaScript Tutorial 4 -Decision Making with Control Structures and Statements
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Decision Making
• switch Statements– Controls program flow by executing a specific set
of statements, depending on the value of an expression
– Syntax switch (expression) {case label1:
statement(s);break;case label2:statement(s);break;default:statement(s);
}
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Decision Making
• switch Statements– Case labels
• Identify specific code segments• Can use a variety of data types as case labels
– Break statement• Used to exit switch statements
– Default label• Contains statements that execute when the
condition expression doesn’t match any of the case labels
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