用相应的字母数字替换文件名的最后一个字母

Question

I am working on a renamer application which is doing various stuff using Javascript . Application gives me this function by default function(index, item) { } and I have to write my code in there, which could looks like this function(index, item) {return item.newBasename...etc} .

What I want to do is to replace the last letter of a filename , to its corresponding alphabet number . For example from "Filename AA " to "Filename A1 ".

Based on this example below, how can I do this?

function(index, item) {
    return item.newBasename.replace(???);
}

Answer 1

You can use String.prototype.replace with a regular expression to match the last letter of the filename, and a function to find the corresponding letter position in the alphabet.

For example:

 const basename = 'hello-world'.replace(/([az])$/i, l => 'abcdefghijklmnopqrstuvwxyz'.indexOf(l.toLowerCase()) + 1); console.log(basename);

Answer 2

I finally found the solution...

function(index, item) {
    str=item.newBasename;
    num=str.toUpperCase().slice(-1).charCodeAt(0) - 64;
    if (num>0 && num < 27) str = str.slice(0, str.length - 1) + num;
    return str; 
}