Basic JavaScript counter

Question

I am new to JavaScript and wondered if there is a more streamlined way of writing this code:

var choices = "ABBCD" // A string containing the letters A-D
var total = 0
function calculate() { // Iterate through choices and add to total depending on the letter
 for (var i=0; i<choices.length; i++) {
 if (choices[i]=="A") {
 total+=1;
 } if (choices[i]=="B") {
 total+=2;
 } if (choices[i]=="C") {
 total+=3;
 } if (choices[i]=="D") {
 total+=4;
 }
 }
}

Answer 1

Good: Use if-elseif

You are calling 4 if statements with your code even if the 1st one is true. These are all mutually exclusive statements so use if-elseif

for (var i=0; i<choices.length; i++) {
 if (choices[i]=="A") {
 total+=1;
 } else if (choices[i]=="B") {
 total+=2;
 } else if (choices[i]=="C") {
 total+=3;
 } else if (choices[i]=="D") {
 total+=4;
 }
}

Better: Use a switch statement

for (var i=0; i<choices.length; i++) {
 switch (choices[i]) {
 case 'A': 
 total += 1;
 break;
 case 'B': 
 total += 2;
 break;
 case 'C': 
 total += 3;
 break;
 case 'D': 
 total += 4;
 break;
 }
}

Best: Convert the character to its numeric equivalent using its ASCII value

for (var i = 0; i < choices.length; i++) {
 //omitted validation that character is a legal value...
 total += choices[i].charCodeAt(0) - 64;
}

• ggordon: Love the idea of using ASCII, really helpful - thanks!
• ggordon: One more question, why is using the switch statement preferable?
• yitzih: @ggordon for most people it is easier to read a switch statement rather than a group of if-else statements. You are doing it based off the value in a variable as opposed to multiple conditions so a switch is well suited here.