I am doing the FreeCodeCamp courses and am confused as to why my code doesn't work. It seems to be a messier version of the correct answer. Below is the correct answer and underneath that is mine. I just want to understand.
Here is the correct answer:
var count = 0;
function cc(card) {
{
case 2:
case 3:
case 4:
case 5:
case 6:
return count++;
case 7:
case 8:
case 9:
return count;
case 10:
case 'J':
case 'Q':
case 'K':
case 'A':
return count--;
}
}
Here is my answer:
var count = 0;
function cc(card) {
// Only change code below this line
switch (card) {
case 2:
return count + 1;
case 3:
return count + 1;
case 4:
return count + 1;
case 5:
return count + 1;
case 6:
return count + 1;
case 7:
return count + 0;
case 8:
return count + 0;
case 9:
return count + 0;
case 10:
return count - 1;
case 'J':
return count - 1;
case 'Q':
return count - 1;
case 'K':
return count - 1;
case 'A':
return count - 1;
}
if (count <= 0){
return count + " hold";
} else {
return count + " bet";
}
Two differences; what you get back and what is modified
count++ and count-- give you back the value of count, then modify count
count + 1 and count - 1 give you back a calculated value based on count and do not modify count
Consider
let x = 1;
x++; // 1
x; // 2
vs
let x = 1;
x + 1; // 2
x; // 1
It is also worth noting that the unary increment and decrement operators can be used prefix, which performs the modification before you get back the value, i.e.
let x = 1;
++x; // 2
x; // 2
Furthermore, please notice that it is impossible to reach your condition if (count <= 0) ... assuming card in [2-9JQKA]|10 as an earlier return will always have been called.
Finally, as I can't see the input I can not be sure on this, however it looks like this code is mixing Number and String. It may be wise to consider choosing just one type so you do not get unexpected behaviour.
Depending on the behaviour you require for A, I would suggest either using Number and mapping {J: 11, Q: 12, K: 13, A: 14}, or doing everything in String.
var count = 0;
function cc(card) {
switch(card) {
case 2:
case 3:
case 4:
case 5:
case 6:
count += 1;
break;
case 7:
case 8:
case 9:
count += 0;
break;
case 10:
case 'J':
case 'Q':
case 'K':
case 'A':
count -= 1;
break;
}
return count + (count > 0 ? " Bet" : " Hold");
}
Related
Im new to coding and javascript, atm im doing som tests in school.
I have this function with two different switch cases with strings which i want to add together and return. But it only returns one of the strings. If i use switch(card.value) on the first and switch(card.suit) on the second it only returns the first one. But if i take it away on the frist one:
switch(value) and switch(card.suit) it return string from the lower switch-case. Why is that? And how do i get it to return A♥? Here is the code. Sorry for my messy description.
const prettyCard = function (card) {
let suit, value
switch (card.value) {
case 1:
return 'A';
break;
case 10:
return 'T';
break;
case 11:
return 'J';
break;
case 12:
return 'Q';
break;
case 13:
return 'K';
break;
case 2:
return '2';
break;
case 3:
return '3';
break;
case 4:
return '4';
break;
case 5:
return '5';
break;
case 6:
return '6';
break;
case 7:
return '7';
break;
case 8:
return '8';
break;
case 9:
return '9';
break;
}
switch (card.suit) {
case 'HEARTS':
return '♥';
break;
case 'SPADES':
return '♠';
break;
case 'DIAMONDS':
return '♦';
break;
case 'CLUBS':
return '♣';
break;
}
return value + suit
}
console.log(prettyCard({ suit: 'HEARTS', value: 1 }))
In addition to the fix suggested in comments, the code can shrink considerably by looking-up suits and values in an object, rather than a long switch.
const prettyCard = card => {
const values = { 1: 'A', 11: 'J', 12: 'Q', 13: 'K' }
const suits = { 'HEARTS': '♥', 'SPADES': '♠', 'DIAMONDS': '♦', 'CLUBS': '♣' };
const suit = suits[card.suit];
const value = card.value > 1 && card.value < 11 ? `${card.value}` : values[card.value];
return { suit, value };
}
console.log(prettyCard({ value: 12, suit: 'HEARTS' }))
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;
}
I currently have this code below, it is supposed to emulate a card counting system, in which different characters increment/decrement the count when passed. The code below runs successfully, but when I attempt console.log(cc(2,3,4,5,6); it returns 1 Bet, when I know the code runs 5 Bet, as those characters should increment the count, yet console.log does not return the accurate count, I assume this is due to scope? But I would like if someone could explain why count isn't accurately returned.
var count = 0;
function cc(card) {
switch(card) {
case 2:
case 3:
case 4:
case 5:
case 6:
count += 1;
break;
case 7:
case 8:
case 9:
count += 0;
break;
case 10:
case 'J':
case 'Q':
case 'K':
case 'A':
count -= 1;
break;
}
if (count > 0) {
return count + " Bet";
}
else {
return count + " Hold";
}
}
cc(2,3,4,5,6); \\ returns 5 Bet
console.log(cc(2,3,4,5,6)); \\ returns 2 Bet
var count = 0;
const bet = card => {
switch (card) {
case 2:
case 3:
case 4:
case 5:
case 6:
count += 1;
break;
case 7:
case 8:
case 9:
count += 0;
break;
case 10:
case "J":
case "Q":
case "K":
case "A":
count -= 1;
break;
}
};
function cc(...moves) {
moves.forEach(bet);
if (count > 0) {
return count + " Bet";
} else {
return count + " Hold";
}
}
console.log(cc(2, 3, 4, 5, 6)); // returns 5 Bet
console.log(cc(2, 3, 4, 5, 6)); // returns 10 Bet
Use arguments or splat operator to get all arguments passed and then loop it:
function cc(...cards) {
var count = 0;
var card;
for (var i = 0; i < cards.length; i++) {
card = cards[i];
switch (card) {
case 2:
case 3:
case 4:
case 5:
case 6:
count += 1;
break;
case 7:
case 8:
case 9:
count += 0;
break;
case 10:
case 'J':
case 'Q':
case 'K':
case 'A':
count -= 1;
break;
}
}
if (count > 0) {
return count + " Bet";
} else {
return count + " Hold";
}
}
cc(2, 3, 4, 5, 6); // returns 5 Bet
console.log(cc(2, 3, 4, 5, 6)); // returns 2 Bet
You have two major problems.
First, your count need to start at zero every time you call cc(). Because you have declared count outside the function, its values is preserved between calls to cc(). By declaring it inside the function, it's initialized to zero before it starts counting the card values.
(Unless you want to continue to the previous count, in which case you should keep it declared outside the function)
Second, your function only accepts one argument. You need to make it accept a list of arguments. This can be done simply with the spread operator .... Then you need to loop through each card value and do the count.
function cc(...cards) { // accept a list of card values as arguments.
let count = 0
for (const card of cards) { // loop through all card values.
switch (card) {
case 2:
case 3:
case 4:
case 5:
case 6:
count += 1
break
case 7:
case 8:
case 9:
count += 0
break
case 10:
case 'J':
case 'Q':
case 'K':
case 'A':
count -= 1
break
}
}
if (count > 0) {
return `${count} Bet`
}
return `${count} Hold`
}
cc(2, 3, 4, 5, 6) // returns 5 Bet
console.log(cc(2, 3, 4, 5, 6)) // returns 5 Bet
console.log(cc(2, 3, 4, 5, 6)) // returns 5 Bet
I'm creating a panel and there are stats for memory, CPU and HDD. I'm using a switch statement and in the case method, I'm putting the current usage of CPU, memory and HDD.
However, the problem is that I'm using operators and I don't know which operator to use because I've tried all of them and I didn't get the results that I expected.
And this is the code: https://pastebin.com/YaxCm0Be
switch(true){
case (mem_percent_get <= 0.01):
var mem_progress_color = 'progress-bar-primary';
break;
case (mem_percent_get <= 33):
var mem_progress_color = 'progress-bar-success';
break;
case (mem_percent_get <= 66):
var mem_progress_color = 'progress-bar-warning';
break;
case (mem_percent_get <= 80):
var mem_progress_color = 'progress-bar-danger';
break;
default:
mem_progress_color = 'progress-bar-theme';
}
switch(true){
case (cpu_percent_get <= 33):
var cpu_progress_color = 'progress-bar-success';
break;
case (cpu_percent_get <= 66):
var cpu_progress_color = 'progress-bar-warning';
break;
case (cpu_percent_get <= 80):
var cpu_progress_color = 'progress-bar-danger';
break;
default:
cpu_progress_color = 'progress-bar-primary';
}
switch(true){
case hdd_percent_get <= 0.01:
var hdd_progress_color = 'progress-bar-primary';
break;
case hdd_percent_get <= 30:
var hdd_progress_color = 'progress-bar-success';
break;
case hdd_percent_get <= 60:
var hdd_progress_color = 'progress-bar-warning';
break;
case hdd_percent_get <= 80:
var hdd_progress_color = 'progress-bar-danger';
break;
default:
hdd_progress_color = 'progress-bar-theme';
}
Well, my first comment is to not use a switch in this case. What you are doing is essentially if () { } else if() {} blocks. You should be using switch when you have a value that you want to strictly check against. I suggest looking into at the MDN docs for switch.
Secondly, from what I can gather is that for the memory, you need it to be red when the value is 1696 / 2098 (80.83%). All of your if/elseif cases rely on <= which would mean that the value must be less than or equal to the number on the right of the equation. In your case, you are looking for <= 80, and without seeing how you calculate mem_percent_get (if it is in the pastebin, I'm unable to open that on my current network), you're value is likely above 80.
For your danger, you likely want 80-100+% as being red, so you should be using >= or greater than or equal to operator.
MDN has an excellent resources on comparison operators.
Created a getClassName method that accepts a percent and will return a className:
const getClassName = percent => {
switch(true){
case (percent <= 0.01):
return 'progress-bar-primary';
case (percent <= 33):
return 'progress-bar-success';
case (percent <= 66):
return 'progress-bar-warning';
case (percent <= 80):
return 'progress-bar-danger';
default:
return 'progress-bar-theme';
}
}
console.log('0: ', getClassName(0));
console.log('40: ', getClassName(40));
console.log('50: ', getClassName(50));
console.log('80: ', getClassName(80));
console.log('100: ', getClassName(100));
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.