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			317 lines
		
	
	
		
			7.4 KiB
		
	
	
	
		
			JavaScript
		
	
			
		
		
	
	
			317 lines
		
	
	
		
			7.4 KiB
		
	
	
	
		
			JavaScript
		
	
console.log("Hello B322!");
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// [SECTION] if, else if and else Statement
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let numG = -1;
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// if statement
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// executes a statement if a specified condition is true
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if(numG < 0) {
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	console.log('Hello');
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}
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/*
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	Syntax 
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	if(condition){
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		statement
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	}
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*/
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// The result of the expression added in the if's condition must result to true, else, the statement inside if() will not run.
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// You can also check the condition. The expression results to a boolean true because of the use of the less than operator.
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console.log(numG < 0); 
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// results to true and so, the if statement was run.
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numG = 0
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if(numG < 0){
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	console.log('Hello again if numA is 0!')
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};
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// It will not run because the expression now results to false:
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console.log(numG < 0);
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// Another sample
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let city = "New York"
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if(city === "New York"){
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	console.log("Welcome to New York City!");
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}
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// else if Clause 
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/*
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  -Executes a statement if previous conditions are false and if the specified condition is true
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  - The "else if" clause is optional and can be added to capture additional conditions to change the flow of a program. 
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*/
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let numH = 1;
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if(numG < 0) {
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	console.log('Hello');
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} else if (numH > 0) {
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	console.log('Hello from the other side');
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}
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// We were able to run the else if() statement after we evaluated that the if condition was failed. 
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// If the if() condition was passed and run, we will no longer evaluate to else if() and end the process there.
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let numA = -1
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if(numA > 0) {
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	console.log('Hello');
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} else if (numH > 0) {
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	console.log('World');
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}
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//else if() statement was no longer run because the if statement was able to run, the evaluation of the whole statement stops there.
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// Let's update the city variable and look at another example:
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city = "Tokyo"
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if(city === "New York"){
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	console.log("Welcome to New York City!")
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} else if(city === "Tokyo"){
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	console.log("Welcome to Tokyo, Japan!")
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};
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// Since we failed the condition for the first if(), we went to the else if() and checked and instead passed that condition.
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// let num = 10;
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// if (num > 0) {
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// 	if (num < 5){
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// 		console.log("Number is between 0 and 5");
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// 	}else {
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// 		console.log("Number is greater than or equal to 5");
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// 	}
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// }else {
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// 	console.log("Number is less than or equal to 0");
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// }
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// if (num > 0 && num < 5) {
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// 	console.log("Number is between 0 and 5");
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// }else if (num >= 5) {
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// 	console.log("Number is greater than or equal to 5");
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// }else{
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// 	console.log("Number is less than or equal to 0");
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// }
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if(numA > 0) {
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	console.log('Hello');
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} else if (numH === 0) {
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	console.log('World');
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} else {
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	console.log('Again');
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}
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/*
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	Since both the preceding if and else if conditions failed, the else statement was run instead. 
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	Else statements should only be added if there is a preceding if condition.
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*/
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// else {
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// 	console.log("Will not run without an if");
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// }
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// else if (numH === 0) {
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// 	console.log('World');
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// } else {
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// 	console.log('Again');
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// }
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// if, else if and else statements with functions
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/*
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  - Most of the times we would like to use if, else if, and else statements with functions to control the flow of our application
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  - By including them inside functions, we can decide when certain conditions will be checked instead of executing statements when the JavaScript loads.
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  - The "return" statement can be utilized with condtional statements in combination with functions to change values to be used for other features of our application.
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*/
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let message = 'No message.';
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console.log(message);
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function determineTyphoonIntensity(windSpeed) {
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	if (windSpeed < 30) {
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		return 'Not a typhoon yet.';
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	}
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	else if (windSpeed <= 61) {
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		return 'Tropical depression detected.';
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	}
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	else if (windSpeed >= 62 && windSpeed <= 88) {
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		return 'Tropical storm detected.';
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	}
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	else if (windSpeed >= 89 || windSpeed <= 117) {
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		return 'Severe tropical storm detected.';
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	}
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	else {
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		return 'Typhoon detected.';
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	}
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}
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message = determineTyphoonIntensity(110);
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console.log(message);
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/*
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 - We can further control the flow of our program based on conditions and changing variables and results
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 - The initial value of "message" was "No message."
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 - Due to the conditional statements created in the function, we were able to reassign it's value and use it's new value to print a different output.
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- console.warn() is a good way to print warnings in our console that cold help us developers act on certain output within our code
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*/
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if (message == 'Tropical storm detected.') {
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	console.warn(message);
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}
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// [SECTION] Truthy and Falsy
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// -In Javascript a "truthy" value is a value that is considered true when ecnountered in a Boolean context
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// - Values are considered true unless defined otherwise
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// - Falsy values/exceptions for truthy:
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	/*
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		1. false
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		2. 0 
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		3. -0
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		4. ""
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		5. null
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		6. undefined
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		7. NaN
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*/
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// Truthy Examples 
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	// - If the result of an expression in a condition results to a truthy value, the condition retunrs true and the corresponding statements are executed
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	// - Expressions are any unit of code that can bve evaluated to a value
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if (true) {
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	console.log('Truthy');
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}
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if(1) {
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	console.log('Truthy');
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}
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if ([]) {
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	console.log('Truthy');
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}
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// Falsy examples
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if (false) {
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	console.log('Falsy');
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}
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if (0) {
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	console.log('Falsy');
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}
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if (undefined) {
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	console.log('Falsy');
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}
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// [SECTION] Conditional (Ternary) Operator
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/*
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	- The Conditional (Ternary) Operator takes in three operands:
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	- 1. condition
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	  2. expression to execute if the condition is truthy
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	  3. expression to execute if the condition is falsy
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	- it can be used as an alternative to an "if else" statement
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	-Ternary operators have an implicit "return" statement meaning that without the return keyword, the resulting expressions can be stored in a variable. 
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	- It is commonly used for single statement execution.
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*/
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// Single statement execution
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let ternaryResult = (1 < 18) ? true : false;
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console.log("Result of Ternary Operator " + ternaryResult);
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// Multiple statement execution
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/*Both functions perform two seperate tasks which changes the value of the "name" variable and returns the result storing it in the "legalAge"
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*/
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let name; 
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function isOflegalAge() {
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	name = 'John';
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	return 'You are of the legal age limit';
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}
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function isUnderAge() {
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	name = 'Jane';
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	return 'You are under the age limit';
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}
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let age = parseInt(prompt("What is your age?"));
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console.log(age);
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let legalAge = (age > 18) ? isOflegalAge() : isUnderAge();
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console.log("Result of Ternary Operator in functions: " + legalAge + ', ' + name);
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// [SECTION] Switch Statement
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let day = prompt("What day of the week is it today?").toLowerCase();
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console.log(day);
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switch (day) {
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	case 'monday':
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		console.log("The color of the day is red");
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		break;
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	case 'tuesday':
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		console.log("The color of the day is orange");
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		break;
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	case 'wednesday':
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		console.log("The color of the day is yellow");
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		break;
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	case 'thursday':
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		console.log("The color of the day is green");
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		break;
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	case 'friday':
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		console.log("The color of the day is blue");
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		break;
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	case 'saturday':
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		console.log("The color of the day is indigo");
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		break;
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	case 'sunday':
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		console.log("The color of the day is violet");
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		break;
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	default:
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		console.log("Please input a valid day");
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		break;
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}
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// [SECTION] Try-Catch-Finally Statement
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function showIntensityAlert(windSpeed) {
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	try {
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		alerat(determineTyphoonIntensity(windSpeed));
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	} catch (error) {
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		console.log(typeof error);
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		console.warn(error.message);
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	} finally {
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		alert('Intensity updates will show new alert.');
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	}
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}
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showIntensityAlert(56);
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