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how to use switch statment

im new with JS and i read about the switch statement. i dont know how to use it
i got an exercise to complete.
got an array with numbers 1-10 and the result need to be with words like "one","two","three"..
Thats what i got so far :
function sayNum(){
let nameNumber = [1,2,3,4,5,6,7,8,9,10]
let text = '';
for(let i=0;i<nameNumber.length;i++){
switch(numbers) {
case "1":
text = "one";
break;
case "2":
text = "two";
break;
case "3":
text = "three";
break;
case "4":
text='four';
break;
case "5":
text = "five";
break;
case "6":
text = "six";
break;
case "7":
text = "seven";
break;
case "8":
text = "eight";
break;
case "9":
text = "nine";
break;
case "10":
text = "ten";
}
}
return text;
}
sayNum()

You could do it like this, for example:
function sayNum(){
let numbers = [1,2,3,4,5,6,7,8,9,10];
let result = [];
for(let i=0;i<numbers.length;i++) {
switch(numbers[i]) {
case 1:
text = "one";
break;
case 2:
text = "two";
break;
case 3:
text = "three";
break;
case 4:
text = "four";
break;
case 5:
text = "five";
break;
case 6:
text = "six";
break;
case 7:
text = "seven";
break;
case 8:
text = "eight";
break;
case 9:
text = "nine";
break;
case 10:
text = "ten";
break;
}
result.push(text);
}
return result;
}
let namedNumbers = sayNum();
console.info(namedNumbers);
This will:
Add the textual values to an array, representing each number in the source array
Return the resulting array to the caller
Log the result in the console

In the switch statement, you pass an 'expression' into the switch statement. The expression itself can be a string, a number, float, boolean etc. Now, the expression is compared to each of the case clause. And this is a 'strict' comparison. And that is the reason why your code was not working.
Firstly you were passing an undeclared variable, 'numbers' as the switch expression. Instead, you should be passing the ith element of the nameNumber[i] array like so: switch(nameNumber[i]){ }
And, secondly, in each of your case clauses, you are comparing the value to a string like "1", "2". But the switch expression is compared using strict equality === operator, therefore when your nameNumber array contains numbers and not strings, your 'case' clauses should also have numbers and not strings. That means case 1: instead of case "1":.
You can read more about the switch-case here: Switch Statement
I have fixed your code below with the changes I mentioned above. Please run the below code snippet to see how it works. Goodluck!
function sayNum(){
let nameNumber = [1,2,3,4,5,6,7,8,9,10]
let text = '';
for(let i=0;i<nameNumber.length;i++){
switch(nameNumber[i]) {
case 1:
text = "one";
break;
case 2:
text = "two";
break;
case 3:
text = "three";
break;
case 4:
text='four';
break;
case 5:
text = "five";
break;
case 6:
text = "six";
break;
case 7:
text = "seven";
break;
case 8:
text = "eight";
break;
case 9:
text = "nine";
break;
case 10:
text = "ten";
}
console.log(text);
}
return text;
}
sayNum();

Rather than using a switch, use if statement. Because in switch, break statement can be used to jump out of a loop.
let text = '';
function sayNum() {
let nameNumber = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
for (let i = 0; i < nameNumber.length; i++) {
if(nameNumber[i] == 1){
text += `"one",`;
}
if(nameNumber[i] == 2){
text += `"two",`;
}
if(nameNumber[i] == 3){
text += `"three",`;
}
if(nameNumber[i] == 4){
text += `"four",`;
}
if(nameNumber[i] == 5){
text += `"five",`;
}
if(nameNumber[i] == 6){
text += `"six",`;
}
if(nameNumber[i] == 7){
text += `"seven",`;
}
if(nameNumber[i] == 8){
text += `"eight",`;
}
if(nameNumber[i] == 9){
text += `"nine",`;
}
if(nameNumber[i] == 10){
text += `"ten"`;
}
}
}
sayNum();
console.log(text)

How do i make switch and if statement in one function

function texas(val) {
var answer = "";
switch(val) {
case 1:
case 2:
case 3:
var answer = "low";
case 4:
case 5:
case 6:
var answer = "medium";
break;
} else if(val => 7) {
var answer = "Huge"
}
return answer;
}
it says error Declaration or statement expected. ts(1128) [13, 7]
and it poits at the else if statement

You can use the "default" keyword, but you should probably update your code in order to handle the cases in which the value of the parameter is not positive or not a number:
function texas(val) {
if (val <= 0 || isNan(val)) {
throw new InvalidOperationException("val should be a positive number");
}
switch(val) {
case 1:
case 2:
case 3:
return "low";
case 4:
case 5:
case 6:
return "medium";
default:
return "Huge"
}
}

It's >= and the elsehas to be deleted. The varfor answer is unnecesary, just declare it once with let. You forgot the break in case 3:.
function texas(val) {
let answer = "";
switch(val) {
case 1:
case 2:
case 3:
answer = "low";
break;
case 4:
case 5:
case 6:
answer = "medium";
break;
}
if(val >= 7) {
answer = "Huge"
}
return answer;
}
console.log(texas(2));
console.log(texas(8));

You just need to return in the switch
function texas(val) {
var answer = "";
switch(val) {
case 1:
case 2:
case 3:
var answer = "low";
return answer;
case 4:
case 5:
case 6:
var answer = "medium";
return answer;
}
if(val => 7) {
var answer = "Huge"
}
return answer;
}

The syntax does not allow to put an else after a switch. else only makes sense in combination with an if statemen. But switch has a default: case which most closely matches your intention (hopefully):
function texas(val) {
var answer = "";
switch(val) {
case 1:
case 2:
case 3:
var answer = "low";
break;
case 4:
case 5:
case 6:
answer = "medium";
break;
default:
if(val >= 7) {
answer = "Huge"
}
// decide what should happen if val is 0, -1 or not even a number (e.g. texas('gotcha!')
break;
}
return answer;
}
Don't forget to put break in your cases, otherwise execution will "fall through" and execute the next cases. You would never end up with "low"

You can't use an if statement within a switch block.
You do have the default option tho -
function texas(val) {
var answer = "";
switch(val) {
case 1:
case 2:
case 3:
answer = "low";
case 4:
case 5:
case 6:
answer = "medium";
break;
default:
answer = val >= 7 ? "Huge" : "Invalid";
break;
}
return answer;
Note that if you have a minus / negative answer, it'll also fall into this clause, but you can the the value of answer with an inline ?: if statement...

You can't put the else after the switch block as people have stated above. switch statement is better for multi way branching and fixed data values. On the other side, if statement is better for boolean values. You can do something like this. It might not be the shortest line of codes, but just so you that there's another approach:
function texas(val) {
let answer = "";
switch (true) {
case (val == 1 || val == 2 || val == 3):
answer = "low";
break;
case (val == 4 || val == 5 || val == 6):
answer = "medium";
break;
case (val >= 7):
answer = "huge";
break;
}
return answer;
}

Javascript - Rock, Paper, scissors with switch statement? If not what are alternatives?

I am running the following codes bellow it only prints 'Draw!' the other cases does not work, what am I doing wrong?
const rps = (p1, p2) => {
var s = 'scissors';
var p = 'paper';
var r = 'rock';
var ans = '';
switch (rps) {
case (p1 == p && p2 == r):case (p1 == s && p2 == p): case (p1 == r && p2 == s):
ans = ('Player 1 won!');
break;
case (p1 == s && p2 == r): case (p1 == r && p2 == p): case (p1 == p && p2 == s):
ans = ('Player 2 won!');
break;
default: ans = ('Draw!');
break;
}
return ans
}
rps('paper','scissors')

switch compares the value you put in (rps which is a function) with each case (which will be true or false).
Since the function never matches a boolean, you always end up hitting the default case.
what am I doing wrong?
Trying to use switch for something it isn't really suited to.
Use if and else instead.

let rock = 2;
let scissors = 4;
let paper = 8;
let firstPlayerChoice = rock;
let secondPlayerChoice = paper;
switch (firstPlayerChoice / secondPlayerChoice) {
case 1:
console.log('there is a tie! pick again');
break;
case 0.5:
case 4:
console.log(`first player won!`);
break;
case 2:
case 0.25:
console.log(`second player won!`);
break;
default:
console.log('something went wrong!');
}

¡Hello!,
You are misunderstanding the use of "switch", the switch works like this:
The switch expression is evaluated once.
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.
Soruce: https://www.w3schools.com/js/js_switch.asp
Like Quentin says, use "if" instead

Simplifying Long Switch Statements

I need to brush up on my javascript because it is my weakest language, so I thought "Hey lets make a simple 'translating' program to test my skills". Well I was able to make it translate one way so far(I havent worked on untranslating the stuff people input), but anyway the way it does it is by a series of many cases inside a switch. Im wondering if there is anyway I can simplify the code instead of having a million switch cases. Thanks here is my code.
function main() {
var get = prompt("Enter what you would like to encode!","At the current time decoding is still a WIP").toLowerCase();
var ina = [...get];
for(i = 0; i < ina.length; i++) {
switch(ina[i]) {
case "a":
ina[i] = "z";
break;
case "b":
ina[i] = "y";
break;
case "c":
ina[i] = "x";
break;
case "d":
ina[i] = "w";
break;
case "e":
ina[i] = "v";
break;
case "f":
ina[i] = "u";
break;
case "g":
ina[i] = "t";
break;
case "h":
ina[i] = "s";
break;
case "i":
ina[i] = "r";
break;
case "j":
ina[i] = "q";
break;
case "k":
ina[i] = "p";
break;
case "l":
ina[i] = "o";
break;
case "m":
ina[i] = "n";
break;
case "n":
ina[i] = "m";
break;
case "o":
ina[i] = "l";
break;
case "p":
ina[i] = "k";
break;
case "q":
ina[i] = "j";
break;
case "r":
ina[i] = "i";
break;
case "s":
ina[i] = "h";
break;
case "t":
ina[i] = "g";
break;
case "u":
ina[i] = "f";
break;
case "v":
ina[i] = "e";
break;
case "w":
ina[i] = "d";
break;
case "x":
ina[i] = "c";
break;
case "y":
ina[i] = "b";
break;
case "z":
ina[i] = "a";
break;
default:
ina[i] = ina[i]
};
};
var outa = ina.join("");
document.getElementById("output").innerHTML = outa;
};

You could use an object with properties like
{
a: 'z',
b: 'y',
c: 'x',
// ...
z: 'a'
}
Usage with the default value of ina[i].
ina[i] = object[ina[i]] || ina[i];

You could use a couple string variables to map the letters.
function translateLetter(input) {
const untranslated = "abcdefghijklmnopqrstuvwxyz";
const translated = "zyxwvutsrqponmlkjihgfedcba";
var i = untranslated.indexOf(input);
return translated[i];
}

The switch you're using has logic that can be implemented directly without needing the switch at all via simple math (I believe most modern JS interpreters should JIT away the actual method calls if this is a hot loop, so the cost there should be trivial):
var get = prompt("Enter what you would like to encode!","At the current time decoding is still a WIP").toLowerCase();
var ina = [...get];
for(i = 0; i < get.length; i++) {
var code = get.charCodeAt(i);
if (97 <= code && code <= 122) { // 'a' and 'z' ordinal values
// Invert lowercase letters with simple math and convert back to character
ina[i] = String.fromCharCode((122 + 97) - code);
}
// No need to handle non-lowercase/non-ASCII since ina initialized to match get
}

Just do the math on the ASCII character codes:
function main() {
var get = prompt("Enter what you would like to encode!","At the current time decoding is still a WIP").toLowerCase();
var ina = [...get];
for (i = 0; i < get.length; i++) {
var charNum = get.charCodeAt(i) - 96;
if (charNum > 0 && charNum < 27) {
ina[i] = String.fromCharCode((27 - charNum) + 96);
}
};
var outa = ina.join("");
document.getElementById("output").innerHTML = outa;
};

Javascript case statement in the switch Statement

I have a problem with the 'case' statement in the 'switch' statement in java script.
My question is how to write more than one number in the 'case' statement and save all the work on writing multiple of commands for each number , ill try to explain myself better. i want to write in the case statement the
number 10-14 (10,11,12,13,14).
how can i write it?
thanks for helping and sorry for my bad english.
name = prompt("What's your name?")
switch (name)
{
case "Ori":
document.write("<h1>" + "Hello there Ori" + "<br>")
break;
case "Daniel":
document.write("<h1>" + "Hi, Daniel." + "<br>")
break;
case "Noa":
document.write("<h1>" + "Noa!" + "<br>")
break;
case "Tal":
document.write("<h1>" + "Hey, Tal!" + "<br>")
break;
default:
document.write("<h1>" + name + "<br>")
}
age = prompt ("What's your age?")
switch (age)
{
case "10":
document.write("you are too little" + name)
break;
case "14":
document.write("So , you are in junior high school" + name)
break;
case "18":
document.write("You are a grown man" + name)
break;
default:
document.write("That's cool" + name)
break;
}

Check out this answer Switch on ranges of integers in JavaScript
In summary you can do this
var x = this.dealer;
switch (true) {
case (x < 5):
alert("less than five");
break;
case (x > 4 && x < 9):
alert("between 5 and 8");
break;
case (x > 8 && x < 12):
alert("between 9 and 11");
break;
default:
alert("none");
break;
}
but that sort of defeats the purpose of a switch statement, because you could just chain if-else statments. Or you can do this:
switch(this.dealer) {
case 1:
case 2:
case 3:
case 4:
// Do something.
break;
case 5:
case 6:
case 7:
case 8:
// Do something.
break;
default:
break;
}

use this, if you dont provide break then control will fall down, In this way you can match for group of numbers in switch.
case 10:
case 11:
case 12:
case 14:
case 15: document.write("i am less than or equal to 15");break;

Say you wanted to switch on a number 10-14 (10,11,12,13,14) you can chain the cases together:
switch(number) {
case 10:
case 11:
case 12:
case 13:
case 14:
alert("I'm between 10 and 14");
break;
default:
alert("I'm not between 10 and 14");
break;
}

You can simply omit the break; statement.
switch (2) {
case 1: case 2: case 3:
console.log('1 or 2 or 3');
break;
default:
console.log('others');
break;
}
I wanted to play with the concept a bit, I do not recommend this approach, however you could also rely on a function that will create a control flow function for you. This simply allows some syntaxic sugar.
var createCaseFlow = (function () {
var rangeRx = /^(\d)-(\d)$/;
function buildCases(item) {
var match = item.match(rangeRx),
n1, n2, cases;
if (match) {
n1 = parseInt(match[1], 10);
n2 = parseInt(match[2], 10);
cases = [];
for (; n1 <= n2; n1++) {
cases.push("case '" + n1 + "':");
}
return cases.join('');
}
return "case '" + item + "':";
}
return function (cases, defaultFn) {
var fnStrings = ['switch (value.toString()) { '],
k;
for (k in cases) {
if (cases.hasOwnProperty(k)) {
fnStrings.push(k.split(',').map(buildCases).join('') + "return this[0]['" + k + "'](); break;");
}
}
defaultFn && fnStrings.push('default: return this[1](); break;');
return new Function('value', fnStrings.join('') + '}').bind(arguments);
};
})();
var executeFlow = createCaseFlow({
'2-9': function () {
return '2 to 9';
},
'10,21,24': function () {
return '10,21,24';
}
},
function () {
return 'default case';
}
);
console.log(executeFlow(5)); //2 to 9
console.log(executeFlow(10)); //10,21,24
console.log(executeFlow(13)); //default case

You have already gotten a few answers on how to make this work. However, I want to point out a few more things. First off, personally, I wouldn't use a switch/case statement for this as there are so many similar cases – a classic if/elseif/else chain feels more appropriate here.
Depending on the use-case you could also extract a function and then use your switch/case (with more meaningful names and values, of course):
function getCategory (number) {
if(number > 20) {
return 3;
}
if(number > 15) {
return 2;
}
if(number > 8) {
return 1;
}
return 0;
}
switch( getCategory( someNumber ) ) {
case 0:
// someNumber is less than or equal to 8
break;
case 1:
// someNumber is any of 9, 10, 11, 12, 13, 14, 15
break;
// ...
}
If the intervals are equally spaced, you could also do something like this:
switch( Math.floor( someNumber / 5 ) ) {
case 0:
// someNumber is any one of 0, 1, 2, 3, 4
break;
case 1:
// someNumber is any one of 5, 6, 7, 8, 9
break;
// ...
}
Also, it should be noted that some people consider switch/case statements with fall-throughs (= leaving out the break; statement for come cases) bad practice, though others feel it's perfectly fine.