add prefix 0 to three-digit numbers

console.log("Hello World!");
let src = `1号
2号
11号
12号
111号
123号`;

let target = src.replace(/^(?:(\d)|(\d\d)|(\d{3}))(?=号)/gm,'00$1,0$2,$3');
console.log(target, '\n------------------');

target = target.replace(/0*,/gm, '');
console.log(target);

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add prefix 0 to three-digit numbers

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