Develop Reference

What is empty switch case in javascript [duplicate]

I need multiple cases in switch statement in JavaScript, Something like:
switch (varName)
{
case "afshin", "saeed", "larry":
alert('Hey');
break;
default:
alert('Default case');
break;
}
How can I do that? If there's no way to do something like that in JavaScript, I want to know an alternative solution that also follows the DRY concept.

Use the fall-through feature of the switch statement. A matched case will run until a break (or the end of the switch statement) is found, so you could write it like:
switch (varName)
{
case "afshin":
case "saeed":
case "larry":
alert('Hey');
break;
default:
alert('Default case');
}

This works in regular JavaScript:
function theTest(val) {
var answer = "";
switch( val ) {
case 1: case 2: case 3:
answer = "Low";
break;
case 4: case 5: case 6:
answer = "Mid";
break;
case 7: case 8: case 9:
answer = "High";
break;
default:
answer = "Massive or Tiny?";
}
return answer;
}
theTest(9);

Here's different approach avoiding the switch statement altogether:
var cases = {
afshin: function() { alert('hey'); },
_default: function() { alert('default'); }
};
cases.larry = cases.saeed = cases.afshin;
cases[ varName ] ? cases[ varName ]() : cases._default();

In Javascript to assign multiple cases in a switch, we have to define different case without break inbetween like given below:
<script>
function checkHere(varName){
switch (varName)
{
case "saeed":
case "larry":
case "afshin":
alert('Hey');
break;
case "ss":
alert('ss');
break;
default:
alert('Default case');
break;
}
}
</script>
Please see example click on link

I like this for clarity and a DRY syntax.
varName = "larry";
switch (true)
{
case ["afshin", "saeed", "larry"].includes(varName) :
alert('Hey');
break;
default:
alert('Default case');
}

If you're using ES6, you can do this:
if (['afshin', 'saeed', 'larry'].includes(varName)) {
alert('Hey');
} else {
alert('Default case');
}
Or for earlier versions of JavaScript, you can do this:
if (['afshin', 'saeed', 'larry'].indexOf(varName) !== -1) {
alert('Hey');
} else {
alert('Default case');
}
Note that includes won't work in some browser including older IE versions, but you could patch things up fairly easily. See the question determine if string is in list in javascript for more information.

My situation was something akin to:
switch (text) {
case SOME_CONSTANT || ANOTHER_CONSTANT:
console.log('Case 1 entered');
break;
case THIRD_CONSTANT || FINAL_CONSTANT:
console.log('Case 2 entered');
break;
default:
console.log('Default entered');
}
The default case always entered. If you're running into a similar multi-case switch statement issue, you're looking for this:
switch (text) {
case SOME_CONSTANT:
case ANOTHER_CONSTANT:
console.log('Case 1 entered');
break;
case THIRD_CONSTANT:
case FINAL_CONSTANT:
console.log('Case 2 entered');
break;
default:
console.log('Default entered');
}

Adding and clarifying Stefano's answer, you can use expressions to dynamically set the values for the conditions in switch, e.g.:
var i = 3
switch (i) {
case ((i>=0 && i<=5) ? i : -1):
console.log('0-5');
break;
case 6: console.log('6');
}
So in your problem, you could do something like:
var varName = "afshin"
switch (varName) {
case (["afshin", "saeed", "larry"].indexOf(varName)+1 && varName):
console.log("hey");
break;
default:
console.log('Default case');
}
Although it is so much DRY...

In Node.js it appears that you are allowed to do this:
data = "10";
switch(data){
case "1": case "2": case "3": // Put multiple cases on the same
// line to save vertical space.
console.log("small");
break;
case "10": case "11": case "12":
console.log("large");
break;
default:
console.log("strange");
break;
}
This makes for much more compact code in some cases.

I use it like this:
switch (true){
case /Pressure/.test(sensor):
{
console.log('Its pressure!');
break;
}
case /Temperature/.test(sensor):
{
console.log('Its temperature!');
break;
}
}

Some interesting methods. For me the best way to solve is using .find.
You can give an indication of what the multiple cases are by using a suitable name inside your find function.
switch (varName)
{
case ["afshin", "saeed", "larry"].find(firstName => firstName === varName):
alert('Hey');
break;
default:
alert('Default case');
break;
}
Other answers are more suitable for the given example but if you have multiple cases to me this is the best way.

It depends. Switch evaluates once and only once. Upon a match, all subsequent case statements until 'break' fire no matter what the case says.
var onlyMen = true;
var onlyWomen = false;
var onlyAdults = false;
(function(){
switch (true){
case onlyMen:
console.log ('onlymen');
case onlyWomen:
console.log ('onlyWomen');
case onlyAdults:
console.log ('onlyAdults');
break;
default:
console.log('default');
}
})(); // returns onlymen onlywomen onlyadults
<script src="https://getfirebug.com/firebug-lite-debug.js"></script>

You can use the 'in' operator...
It relies on the object/hash invocation, so it's as fast as JavaScript can be.
// Assuming you have defined functions f(), g(a) and h(a,b)
// somewhere in your code,
// you can define them inside the object, but...
// the code becomes hard to read. I prefer it this way.
o = { f1:f, f2:g, f3:h };
// If you use "STATIC" code can do:
o['f3']( p1, p2 )
// If your code is someway "DYNAMIC", to prevent false invocations
// m brings the function/method to be invoked (f1, f2, f3)
// and you can rely on arguments[] to solve any parameter problems.
if ( m in o ) o[m]()

You can do this:
alert([
"afshin",
"saeed",
"larry",
"sasha",
"boby",
"jhon",
"anna",
// ...
].includes(varName)? 'Hey' : 'Default case')
or just a single line of code:
alert(["afshin", "saeed", "larry",...].includes(varName)? 'Hey' : 'Default case')
a little improvement from ErikE's answer

I can see there are lots of good answers here, but what happens if we need to check more than 10 cases? Here is my own approach:
function isAccessible(varName){
let accessDenied = ['Liam', 'Noah', 'William', 'James', 'Logan', 'Benjamin',
'Mason', 'Elijah', 'Oliver', 'Jacob', 'Daniel', 'Lucas'];
switch (varName) {
case (accessDenied.includes(varName) ? varName : null):
return 'Access Denied!';
default:
return 'Access Allowed.';
}
}
console.log(isAccessible('Liam'));

The problem with the above approaches, is that you have to repeat the several cases every time you call the function which has the switch. A more robust solution is to have a map or a dictionary.
Here is an example:
// The Map, divided by concepts
var dictionary = {
timePeriod: {
'month': [1, 'monthly', 'mensal', 'mês'],
'twoMonths': [2, 'two months', '2 months', 'bimestral', 'bimestre'],
'trimester': [3, 'trimesterly', 'quarterly', 'trimestral'],
'semester': [4, 'semesterly', 'semestral', 'halfyearly'],
'year': [5, 'yearly', 'annual', 'ano']
},
distance: {
'km': [1, 'kms', 'kilometre', 'kilometers', 'kilometres'],
'mile': [2, 'mi', 'miles'],
'nordicMile': [3, 'Nordic mile', 'mil (10 km)', 'Scandinavian mile']
},
fuelAmount: {
'ltr': [1, 'l', 'litre', 'Litre', 'liter', 'Liter'],
'gal (imp)': [2, 'imp gallon', 'imperial gal', 'gal (UK)'],
'gal (US)': [3, 'US gallon', 'US gal'],
'kWh': [4, 'KWH']
}
};
// This function maps every input to a certain defined value
function mapUnit (concept, value) {
for (var key in dictionary[concept]) {
if (key === value ||
dictionary[concept][key].indexOf(value) !== -1) {
return key
}
}
throw Error('Uknown "'+value+'" for "'+concept+'"')
}
// You would use it simply like this
mapUnit("fuelAmount", "ltr") // => ltr
mapUnit("fuelAmount", "US gal") // => gal (US)
mapUnit("fuelAmount", 3) // => gal (US)
mapUnit("distance", "kilometre") // => km
// Now you can use the switch statement safely without the need
// to repeat the combinations every time you call the switch
var foo = 'monthly'
switch (mapUnit ('timePeriod', foo)) {
case 'month':
console.log('month')
break
case 'twoMonths':
console.log('twoMonths')
break
case 'trimester':
console.log('trimester')
break
case 'semester':
console.log('semester')
break
case 'year':
console.log('year')
break
default:
throw Error('error')
}

One of the possible solutions is:
const names = {
afshin: 'afshin',
saeed: 'saeed',
larry: 'larry'
};
switch (varName) {
case names[varName]: {
alert('Hey');
break;
}
default: {
alert('Default case');
break;
}
}

If your case conditions are complex, many case value matches, or dynamic value match required, then it may be best to move that case matching logic to handler child functions.
In your case, if say you had thousands of usernames to match against for a security permissions check for example, this method is cleaner option, more extensible, exposing the high level multi-way branch logic without getting swamped in a long list of case statements.
switch (varName)
{
case checkPatternAdministrator(varName):
alert('Hey');
break;
case checkPatternUserTypeA(varName):
alert('Hey2');
break;
case checkPatternUserTypeB(varName):
alert('Hey3');
break;
default:
alert('Default case');
break;
}
function checkPatternAdministrator(varName) {
// Logic to check Names against list, account permissions etc.
// return the varName if a match is found, or blank string if not
var matchedAdministratorName = varName;
return matchedAdministratorName;
}

Here is one more easy-to-use switch case statement. which can fulfill your requirement. We can use the find method in the switch statement to get the desire output.
switch(varname){
case["afshin","saeed","larry"].find(name => name === varname):
alert("Hey")
break;
default:
alert('Default case');
break;
}

The switch statement is used to select one of many code blocks to execute based on a condition
the value in the switch expression is compared to the different values provided
if there is a match the code block related to it will be executed
if there is no match the default block is executed
syntax:
switch(expression) {
case x:
// code block
break;
case y:
// code block
break;
default:
// code block
}
NOTE:
It must be noted that if the break statement is omitted then the next block will be executed as well even if they does not match with switch expression. So don't forget to add the break statement at the end of each code block if you don't want to get the specified behaviour
A practical example:
the following code returns the current day of the week in strings based on an integer (provided by 'new Date().getDay()')
switch (new Date().getDay()) {
case 0:
day = "Sunday";
break;
case 1:
day = "Monday";
break;
case 2:
day = "Tuesday";
break;
case 3:
day = "Wednesday";
break;
case 4:
day = "Thursday";
break;
case 5:
day = "Friday";
break;
case 6:
day = "Saturday";
}
the code samples were taken from W3Schools

Another way of doing multiple cases in a switch statement, when inside a function:
function name(varName){
switch (varName) {
case 'afshin':
case 'saeed':
case 'larry':
return 'Hey';
default:
return 'Default case';
}
}
console.log(name('afshin')); // Hey

Cleaner way to handle that
if (["triangle", "circle", "rectangle"].indexOf(base.type) > -1)
{
//Do something
}else if (["areaMap", "irregular", "oval"].indexOf(base.type) > -1)
{
//Do another thing
}
You can do that for multiple values with the same result

Just change the switch condition approach:
switch (true) {
case (function(){ return true; })():
alert('true');
break;
case (function(){ return false; })():
alert('false');
break;
default:
alert('default');
}

<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Example1</title>
<link rel="stylesheet" href="css/style.css" >
<script src="js/jquery-1.11.3.min.js" type="text/javascript"></script>
<script>
function display_case(){
var num = document.getElementById('number').value;
switch(num){
case (num = "1"):
document.getElementById("result").innerHTML = "You select day Sunday";
break;
case (num = "2"):
document.getElementById("result").innerHTML = "You select day Monday";
break;
case (num = "3"):
document.getElementById("result").innerHTML = "You select day Tuesday";
break;
case (num = "4"):
document.getElementById("result").innerHTML = "You select day Wednesday";
break;
case (num = "5"):
document.getElementById("result").innerHTML = "You select day Thusday";
break;
case (num = "6"):
document.getElementById("result").innerHTML = "You select day Friday";
break;
case (num = "7"):
document.getElementById("result").innerHTML = "You select day Saturday";
break;
default:
document.getElementById("result").innerHTML = "You select day Invalid Weekday";
break
}
}
</script>
</head>
<body>
<center>
<div id="error"></div>
<center>
<h2> Switch Case Example </h2>
<p>Enter a Number Between 1 to 7</p>
<input type="text" id="number" />
<button onclick="display_case();">Check</button><br />
<div id="result"><b></b></div>
</center>
</center>
</body>

You could write it like this:
switch (varName)
{
case "afshin":
case "saeed":
case "larry":
alert('Hey');
break;
default:
alert('Default case');
break;
}

For me this is the simplest way:
switch (["afshin","saeed","larry"].includes(varName) ? 1 : 2) {
case 1:
alert('Hey');
break;
default:
alert('Default case');
break;
}

Switch case match with string

function getFieldType(value){
var type = "";
switch(value){
case "TEXT_BOX":
type=FieldTypeEnum.TEXT_BOX;
break;
case "PASSWORD":
type=FieldTypeEnum.PASSWORD;
break;
case "CHECK_BOX":
type=FieldTypeEnum.CHECK_BOX;
break;
case "RADIO_BUTTON":
type=FieldTypeEnum.RADIO_BUTTON;
break;
case "DROP_DOWN":
type=FieldTypeEnum.DROP_DOWN;
break;
case "SEARCH_CARD_BOX":
type=FieldTypeEnum.SEARCH_CARD_BOX;
break;
case "STATE_DROP_DOWN":
type=FieldTypeEnum.STATE_DROP_DOWN;
break;
case "ID_DROP_DOWN":
type=FieldTypeEnum.ID_DROP_DOWN;
break;
case "GENDER_DROP_DOWN":
type = FieldTypeEnum.GENDER_DROP_DOWN;
break;
default:
type = "";
}
return type;
}
I want to combined three drop down box (STATE_DROP_DOWN, ID_DROP_DOWN, GENDER_DROP_DOWN)into one .
Means I want something like below :
case String.endwith("_DROP_DOWN"):
type=FieldTypeEnum.ID_DROP_DOWN;
break;
Is it possible in JavaScript? If yes then how?

It is possible, in a javascript switch/case statement you can compare for string equality (which evaluates to true or false) or more complex statements which just as when testing for string equality, also evaluate to true or false (e.g. String.endwith("_DROP_DOWN")). However personally I would prefer the following:
STATE_DROP_DOWN:
// intentional fall through
ID_DROP_DOWN:
// intentional fall through
GENDER_DROP_DOWN:
//.. do your stuff
break;
I believe this way it is more clearly through which switch case you are falling in a certain situation.

You can put a ternary operator in the case, and test if it ends with "DROP_DOWN" return value otherwise blank string.
switch(value){
case value.endsWith("_DROP_DOWN") ? value : '' {
type=FieldTypeEnum.ID_DROP_DOWN;
break;
}
}

Replace ÅÄÖ (both capital and lowercase) with javascript

I'm trying to replace Å, Ä and Ö in a user input (a column name) variable. This variable need ex. x00e5 for "å" etc for using retrieving columns (by internalName) from SharePoint, therefore I need the correct format.
I'm checking if the input value has any of Å, Ä and Ö (both capital and lower):
switch (inputValue) {
case inputValue.indexOf('å') > -1:
inputValue = inputValue.replace(/å/g, '_x00e5_');
break;
case inputValue.indexOf('Å') > -1:
inputValue = inputValue.replace(/Å/g, '_x00c5_');
break;
case inputValue.indexOf('ä') > -1:
inputValue = inputValue.replace(/ä/g, '_x00e4_');
break;
case inputValue.indexOf('Ä') > -1:
inputValue = inputValue.replace(/Ä/g, '_x00c4_');
break;
case inputValue.indexOf('ö') > -1:
inputValue = inputValue.replace(/ö/g, '_x00e6_');
break;
case inputValue.indexOf('Ö') > -1:
inputValue = inputValue.replace(/Ö/g, '_x00c6_');
break;
default:
break;
}
Even if one case condition is true, it never enters the case.
This cannot be the simplest/best solution for this?

There is no harm in calling replace() if the target substring is not present. So no switch is needed:
inputValue = inputValue
.replace(/å/g, '_x00e5_')
.replace(/Å/g, '_x00c5_')
.replace(/ä/g, '_x00e4_')
.replace(/Ä/g, '_x00c4_')
.replace(/ö/g, '_x00e6_')
.replace(/Ö/g, '_x00c6_');

Switch combining cases string regex and number

Is there a way to create multiple cases in a single Javascript switch statement?
In my code I receive the value of a field via jQuery.
Is it possible that one case checks for string regex and another for number of the same variable?
I am thinking along the lines of:
var field = $(this).val();
var msg;
switch (field)
{
case field.test('Yes'):
msg = "FOO\n";
break;
case 10:
msg = "BAR\n";
break;
}
Although I saw here: Switch statement for string matching in JavaScript
That the way to use switch on strings is by sending the switch statement a "true" value.
What would be the most concise (and correct!) way to achieve this?

OK, compiling both answers above my code that worked and was most elegant IMO is:
var fieldVal = $(this).val();
var msg;
switch (true)
{
case /Yes/.test(fieldVal):
msg = "FOO";
break;
case fieldVal > 10 :
msg = "BAR";
break;
}
this works as separate if statements since we are evaluating whether or not the case returns true but in a clearer and more concise way that could give us the option to add totally disparate test statements in one switch.
the reason it works is probably that the case expression evaluated is interpreted as a true or false value and then checked against the main -
switch(true)

You can't the case need to single value, that's compared to switch expression, but you can put multiple cases to execute the same code:
switch (field) {
case 'Yes':
case 'yes':
case 'YES':
msg = "FOO\n";
break;
case 10:
msg = "BAR\n";
break;
}
but in order to use test as case you can pass true to switch (I found that trick in some open source project):
switch (true) {
case field.test('Yes'):
msg = "FOO\n";
break;
case field == 10:
msg = "BAR\n";
break;
}
but this is the same as if/else

Note: you're using test() incorrectly, it's a method of a regex object, so you need /Yes/.test(field) rather than field.test('Yes'). Anyway...
If you've only got two cases as shown then I'd use an if/else/else if structure:
var field = $(this).val();
var msg;
if(/Yes/.test(field)) {
msg = "FOO\n";
} else if (field === 10) {
msg = "BAR\n";
}
If you need to add additional cases I'd just add extra if else {} branches on the end.
If you have several specific numeric cases you might consider putting them in a switch with the regex tests in a default at the end:
switch (field) {
case 10:
msg = "BAR\n";
break;
case 30:
msg = "whatever\n";
break;
case 50:
msg = "hi\n";
break;
default:
if (/Yes/.test(field)) {
msg = "FOO\n";
else if (/No|N|False|/i.test(field)) {
msg = "blah\n";
}
break;
}
The switch (true) option you alluded to in the question is really just a messier version of an if/else/else if, so it doesn't really make sense unless you have some fall-through cases:
switch(true)
case /Yes/.test(field):
case /Y/.text(field):
case /Whatever/.text(field):
msg = "FOO\n";
break;
case field == 10:
msg = "BAR\n";
break;
}
...and even then an if with multiple conditions joined by || arguably just as tidy with appropriate newlines, and combining multiple regexes into a single one is probably a lot neater.

Switch case - else condition

<script type="text/javascript">
//You will receive a different greeting based
//on what day it is. Note that Sunday=0,
//Monday=1, Tuesday=2, etc.
var d = new Date();
var theDay = d.getDay();
switch (theDay)
{
case 5:
document.write("Finally Friday");
break;
case 6:
document.write("Super Saturday");
break;
case 0:
document.write("Sleepy Sunday");
break;
default:
document.write("I'm looking forward to this weekend!");
}
</script>
If the theDay = 5, then we display Finally Friday. I want if theDay !=5, then display 'Finally Something'.. similarly for others too...
Is it possible without an If/else condition. If the case 5 does not execute, can i do something else in that place?

Is it possible without an If/else condition. If the case 5 does not execute, can i do something else in that place?
No.
The switch statement will execute the first matching case, and then keep going (ignoring all further case labels) until it gets to either a break statement or the end of the switch block - but even though you can "fall through" to subsequent cases by omitting the break statement the switch does not provide any mechanism to say "do something when this case isn't matched/executed, but also keep trying to look for a matching case".
What you are describing would normally be done with a series of if/else statements:
var d = new Date(),
theDay=d.getDay(),
matched = false;
if (theDay === 5) {
matched = true;
document.write("Finally Friday");
} else {
// your != 5 case here
}
if (theDay === 6) {
matched = true;
document.write("Super Saturday");
} else {
// your != 6 case here
}
if (theDay === 0) {
matched = true;
document.write("Sleepy Sunday");
} else {
// your != 0 case here
}
// default when none matched:
if (!matched) {
document.write("I'm looking forward to this weekend!");
}
Note that I've added a matched flag to allow the default to work. And note that there are no else if statements because you need every if/else pair to execute.
If you are really determined to use a switch statement you could do something silly like the following:
var d = new Date(),
theDay = d.getDay(),
c,
cases = { // pre-list all the "not" cases
"!5" : true,
"!6" : true,
"!0" : true
};
// add case for theDay and remove the "not" case for theDay (if there is one)
cases[theDay] = true;
if (cases["!" + theDay])
delete cases["!" + theDay];
for (c in cases) {
switch(c) {
case "5":
document.write("Finally Friday");
break;
case "!5":
document.write("Finally Something");
break;
case "6":
document.write("Super Saturday");
break;
case "!6":
document.write("Finally Something - but not 6");
break;
case "0":
document.write("Sleepy Sunday");
break;
case "!0":
document.write("Finally Something - but not 0");
break;
default:
document.write("I'm looking forward to this weekend!");
}
}
If you need the cases to execute in a specific order use an array rather than an object.

Its like switch does a jump to the matching case, if it doesn't match it will jump to what matches. The answer to your question "If the case 5 does not execute, can i do something else in that place?" is No, because it never reaches that case at all. It jumps to the next matching case or default.

Is it possible without an If/else condition. If the case 5 does not execute, can i do something else in that place?
Use a default code block as seen below. Anything that doesn't match the cases will fallback to the default one.
switch(expression) {
case x:
// code block
break;
case y:
// code block
break;
default:
// code block
}
How this works:
The value of the expression is compared with the values of each case.
If there is a match, the associated block of code is executed.
If there is no match, the default code block is executed.

A standard if/else would be the best way to achieve this. I wonder why you want to do it without.
That said, It's not very elegant, but you could try adding the following to the top of your switch statement:
case 0:
case 1:
case 2:
case 3:
case 4:
case 6:
document.write("Finally Something");
Giving you:
switch (theDay)
{
case 0:
case 1:
case 2:
case 3:
case 4:
case 6:
document.write("Finally Something");
case 5:
document.write("Finally Friday");
break;
case 6:
document.write("Super Saturday");
break;
case 0:
document.write("Sleepy Sunday");
break;
default:
document.write("I'm looking forward to this weekend!");
}

You can do something like:
var something = 0;
switch (theDay) {
case 5:
document.write("Finally Friday");
something = 15;
break;
case 6:
document.write("Super Saturday");
something = 16;
break;
case 0:
document.write("Sleepy Sunday");
something = 20;
break;
default:
document.write("I'm looking forward to this weekend!");
}
switch (something) {
case 15: document.write("Not Friday"); break;
case 16: document.write("Not Saturday"); break;
case 20: document.write("Not Sunday"); break;
default: document.write("Nothing"); break;
}

Overly complicated answers.
Simplify.
var switchElse = true;
switch (CHECK_SOMETHING)
{
case "SOME_VALUE":
...DO SOMETHING...
switchElse = false;
break;
default:
}
if (switchElse)
{
...DO ELSE...
}
The only solution that can be formulated without a compare.
USE "DEFAULT" PATTERN
var myValue = "Friday"
switch (CHECK_SOMETHING)
{
case "SOME_VALUE":
myValue = "Some Other Day";
default:
}