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Compare if az or AZ and output the result using java-script function

I am learning JavaScript. Very new and knowledgable basic. I am playing around with various JavaScript variants.

I am comparing az (lower case) and AZ (upper case) from user input. and providing a base of responses at the entrance.

I can usually do it with this long code:

<script>
var x=prompt("Enter Your character");

switch(x){

case 'a':
case 'b':
case 'c':
case 'd':
case 'e':
case 'f':
case 'g':
case 'h':
case 'i':
case 'j':
case 'k':
case 'l':
case 'm':
case 'n':
case 'o':
case 'p':
case 'q':
case 'r':
case 's':
case 't':
case 'u':
case 'v':
case 'w':
case 'x':
case 'y':
case 'z':
document.write("Lower case");
break;

case 'A':
case 'B':
case 'C':
case 'D':
case 'E':
case 'F':
case 'G':
case 'H':
case 'I':
case 'J':
case 'K':
case 'L':
case 'M':
case 'N':
case 'O':
case 'P':
case 'Q':
case 'R':
case 'T':
case 'U':
case 'V':
case 'W':
case 'X':
case 'Y':
case 'Z':


document.write("Upper case");
break;

default:
document.write("It is number");
break;

}

With a switch, I want to achieve the same output, but with less code! Something like that:

 var x=prompt("Enter Your character");

switch(x){

case x>='a'||x<='z':
document.write("Lower case");
break;

case x>='A'||x<='Z':
document.write("Upper case");
break;

default:
document.write("It is number");
break;

Any help?

Please, I want to do this with just the switch function. I know I can do it with an if / else function, but I want to do it with a switch. If this is not possible with a switch, let me know :-)

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6 answers


The operator switch

compares the input expression with each case argument using strict comparison.

So, use true

inside a switch clause and specify the expressions that are evaluated in the true

case:



var x = prompt("Enter Your character");
switch (true) {
  case x >= "a" && x <= "z":
    alert("Lower case");
    break;
  case x >= "A" && x <= "Z":
    alert("Upper case");
    break;
  default:
    alert("Something else");
    break;
}
Run code


I personally don't recommend this. This is for teaching only.

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You can try something like this.

<script>
var x=prompt("Enter Your character");

if (x.test(/[a-z]/)) {
document.write("Lower case");
} else if (x.test(/[A-Z]/)) {
document.write("Upper case");
} else {
document.write("It is number");
}
</script>


You can see more information here: https://developer.mozilla.org/es/docs/Web/JavaScript/Reference/Global_Objects/RegExp/test

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You can do a simple if / else

var x=prompt("Enter Your character");
if(!isNaN(x))
    console.log("It is number");
else if(x.toLowerCase()==x)
    console.log("Lower case");
else if(x.toUpperCase()==x)
    console.log("Upper case"););
Run code


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Check if a character is between other characters:

var x=prompt("Enter Your character");
if (x >= '0' && x <= '9')
    alert("number!");
else if(x >= 'a' && x <= 'z')
    alert("lowercase!");
else if(x >= 'A' && x <= 'Z')
    alert("uppercase!");
else
    alert("not a letter!");
+1


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The parameter to the operator case

is something that an equality comparison is done for, you don't put a comparison. If you want to make a comparison, use if

rather than switch

. Also, you should combine comparisons with &&

, not|| 

if (x >= 'a' && x <= 'z') {
    document.write('Lower case');
} else if (x >= 'A' && x <= 'Z') {
    document.write('Upper case');
} else if (x >= '0' && x <= '9') {
    documennt.write('Number');
} else {
    document.write('Something else');
}
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Try also:

var x = prompt("Enter Your character");
var find = x.match(/([a-z]*)([A-Z]*)([0-9]*)/);
var type = ["Lower case","Upper case", "It is number"];

document.write(find ? type[find.lastIndexOf(x)-1] : "Unknown char")
Run code


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