How to transform if-else statement to equivalent switch statement? I’m gonna show an example. Take a look at the following if-else statement :
function number(num){
if(num < 0){
alert("Number is negative");
}
else if(num >= 0 && num <= 100){
alert("Number is betwwen 0 and 100 (inclusive)");
}
else if(num > 100){
alert("Number is greater than 100");
}
else{
alert("This is not a number");
}
}
First wrap the if-else inside switch block :
function number(num){
switch(condition){//I'll tell the condition later
if(num < 0){
alert("Number is negative");
}
else if(num >= 0 && num <= 100){
alert("Number is betwwen 0 and 100 (inclusive)");
}
else if(num > 100){
alert("Number is greater than 100");
}
else{
alert("This is not a number");
}
}
}
if and all if-else blocks become our case blocks, and else will become default case :
function number(num
switch(condition){//I'll condition later
case (num < 0) : {
alert("Number is negative");
}
case (num >= 0 && num < 100) : {
alert("Number is betwwen 0 and 100 (inclusive)");
}
case (num > 100) : {
alert("Number is greater than 100");
}
default : {
alert("This is not a number");
}
}
}
And don’t forget to add break :
function number(num
switch(condition){//I'll condition later
case (num < 0) : {
alert("Number is negative");
}
break;
case (num >= 0 && num < 100) : {
alert("Number is betwwen 0 and 100 (inclusive)");
}
break;
case (num > 100) : {
alert("Number is greater than 100");
}
break;
default : {
alert("This is not a number");
}
}
}
All cases are actually boolean (num < 0, num >= 0 && num < 100 and num > 100 are actually returning boolean). One of the case will eventually become true depending on the value of num. So our switch condition should be a boolean (true) so that it will match one of the cases :
function number(num
switch(true){
case (num < 0) : {
alert("Number is negative");
}
break;
case (num >= 0 && num < 100) : {
alert("Number is betwwen 0 and 100 (inclusive)");
}
break;
case (num > 100) : {
alert("Number is greater than 100");
}
break;
default : {
alert("This is not a number");
}
}
}
Done.
