const json = `{"number": "1234567"}`;
const jsonObj = JSON.parse(json);
jsonObj.number = `${jsonObj.number}000`;
console.log(JSON.stringify(jsonObj));
const json = `{"number": "1234567"}`;
const updatedJson = json.replace(/"number":\s?"(\d+)"/, (_, num) => `"number": "${num}000"`);
console.log(json);