### Problem

Given a digit string, return all possible letter combinations that the number could represent. (Check out your cellphone to see the mappings)

### Example

Input : Digit string "23"
Output : ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"].

### JavaScript Code

```function letterCombinations(digits) {
var map = [];
map[2]="abc";
map[3]="def";
map[4]="ghi";
map[5]="jkl";
map[6]="mno";
map[7]="pqrs";
map[8]="tuv";
map[9]="wxyz";
map[0]="";

var result = [];

if(digits == null || digits.length == 0)
return result;

var temp = [];
getString(digits, temp, result, map);

return result;
}

function getString(digits, temp, result, map){
if(digits.length == 0){
var arr = [];
for(var i=0; i<temp.length; i++){
arr[i] = temp[i];
}
result.push(arr.join(''));
return;
}

var curr = parseInt(digits.substring(0,1));
var letters = map[curr];
for(var i=0; i<letters.length; i++){
temp.push(letters.charAt(i));
getString(digits.substring(1), temp, result, map);
temp.pop();
}
}

console.log(letterCombinations("23"));
```

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