JavaScript switch statement and case expression

Question

JavaScript switch statement and case expression

Struggling to use boolean expressions within a switch statement to search for undefined values and manually change them. When using an if statement, the process is easier.

For example: if statement

if(Item1 == undefined)
{
  item1 = "No";
}
else if (Item2 == undefined)
{
  item2 = "No";
}

But when attempting this with a switch statement:

 switch (array) {
 case (item1 == undefined):
 item1 = "No";
 console.log('item1 result', item1 );
 break;
 case item2 == undefined:
 item2 = "No";
 console.log('item2 result', item2 );
 break;
 default:

 }

The switch statement does not execute properly, except when removing == undefined and just using item1. Then it seems to work?

javascript angularjs

Answer 1

Answer №1

The switch statement is unable to evaluate array values in that manner, which is why it does not proceed through the switch statement. To use a switch statement with an array, you must define the specific value from the array that you want to switch.

Additionally, within a case statement, expressions cannot be used; you must provide a direct value instead.

If you still wish to utilize a switch statement for your task, you can implement something like this:

item1 = array[1];
switch(item1) {
    case "undefined":
        // code goes here
    break;
}

However, judging by your example, it seems like you are attempting to verify if certain values are set or not. In such cases, using if statements would be a more suitable choice rather than switch statements.

$arr = []; // Your array
if(typeof $arr[0] == "undefined") {
    $arr[0] = "No";
}

Answer 2

The switch statement is unable to evaluate array values in that manner, which is why it does not proceed through the switch statement. To use a switch statement with an array, you must define the specific value from the array that you want to switch.

Additionally, within a case statement, expressions cannot be used; you must provide a direct value instead.

If you still wish to utilize a switch statement for your task, you can implement something like this:

item1 = array[1];
switch(item1) {
    case "undefined":
        // code goes here
    break;
}

However, judging by your example, it seems like you are attempting to verify if certain values are set or not. In such cases, using if statements would be a more suitable choice rather than switch statements.

$arr = []; // Your array
if(typeof $arr[0] == "undefined") {
    $arr[0] = "No";
}

Answer 3

Answer №2

Only one variable can be used in a switch statement, like so:

switch (element) {
 case 'undefined':
 outcome1 = "Not present";
 console.log('outcome1:', outcome1);
 break;
 case element.length:
 outcome2 = "Not found";
 console.log('outcome2:', outcome2);
 break;

 }

Answer 4

Only one variable can be used in a switch statement, like so:

switch (element) {
 case 'undefined':
 outcome1 = "Not present";
 console.log('outcome1:', outcome1);
 break;
 case element.length:
 outcome2 = "Not found";
 console.log('outcome2:', outcome2);
 break;

 }

Answer 5

Answer №3

Helpful for understanding function arguments.

An efficient and straightforward method would be:

value1 = (value1 === null || value1 === undefined) ? 'no' : value1;
value2 = (value2 === null || value2 === undefined) ? 'no' : value2;

If the variable is either null or undefined, it will assign a default value; otherwise, it will keep the original value.

p.s. This approach checks for null or undefined values and is more concise than using a switch statement.

Answer 6

Helpful for understanding function arguments.

An efficient and straightforward method would be:

value1 = (value1 === null || value1 === undefined) ? 'no' : value1;
value2 = (value2 === null || value2 === undefined) ? 'no' : value2;

If the variable is either null or undefined, it will assign a default value; otherwise, it will keep the original value.

p.s. This approach checks for null or undefined values and is more concise than using a switch statement.

Answer 7

Answer №4

let index = 0;
while(index < myArray.length){
    switch(myArray[index]){
        case "null":
        //continue with other cases
            break;
    }
    index++;
}

Answer 8

let index = 0;
while(index < myArray.length){
    switch(myArray[index]){
        case "null":
        //continue with other cases
            break;
    }
    index++;
}

JavaScript switch statement and case expression

Answer №1

Answer №2

Answer №3

Answer №4

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