firstToLast.js

/*
Coding in function ```firstToLast```, function accept 2 parameters:```str``` and ```c```. ```str``` is a string. ```c``` is a char. 

Please return the gap between the first position of ```c``` and the last position of ```c```.

If there are a lot of ```c``` in the ```str```, should  return a positive integer; If there is only one ```c``` in ```str```, should return 0; If there is no ```c``` in the ```str```, should return -1. Retrieval should not ignored the case.

for example:

```
firstToLast("ababc","a") should return 2(2-0)
firstToLast("ababc","c") should return 0(4-4)
firstToLast("ababc","d") should return -1
*/

//Answer//

let firstToLast = (str, c) => str.lastIndexOf(c) - Math.max(0, str.indexOf(c))

//OR//

let firstToLast = (str,c) => str.indexOf(c)===-1?-1:str.lastIndexOf(c)-str.indexOf(c)