Why Large Snowflake IDs Lose Precision in JavaScript and How to Fix Them

1. Symptom: ID changes after transmission

During front‑back integration, newly added records appear correctly, but attempts to delete or update them silently fail because the ID received by the frontend differs from the one stored in the database.

Scenario

The server generates a 19‑digit Snowflake ID (e.g., 1951211313641689089). The Vue front‑end displays this ID, but when the same ID is sent back for deletion, it becomes 1951211313641689000, with the last digits replaced by zeros.

Investigation steps

Check the server directly with an API testing tool using the real database ID – deletion works, so the backend logic is fine.

Compare the ID shown in the front‑end list with the original database ID – the trailing digits are automatically replaced by zeros.

Identify the root cause: JavaScript’s Number type cannot precisely represent integers larger than Number.MAX_SAFE_INTEGER (9,007,199,254,740,991), leading to precision loss for 18‑19‑digit IDs.

2. Why JavaScript loses precision

JavaScript’s Number type stores values as double‑precision floating‑point numbers, which safely represent up to 16 decimal digits. Snowflake IDs usually exceed this range, so when a backend Long is serialized to JSON and parsed as a Number, the excess digits are rounded or truncated.

3. Four ways to solve the problem

Store IDs as strings

Receive and transmit IDs as strings to avoid any numeric conversion.

const list = res.data.map(item => ({
  ...item,
  id: item.id.toString() // force string
}));

const deleteData = async (id) => {
  await axios.post('/api/delete', { id }); // id is a string, no precision loss
};

Use BigInt (ES2020+)

BigInt represents arbitrarily large integers. Append n or use BigInt(), then convert to string before sending.

// Direct declaration
const bigId = 1951211313641689089n;

// From string (recommended)
const bigId = BigInt("1951211313641689089");

// Send
await axios.post('/api/delete', { id: bigId.toString() });

Third‑party library (bignumber.js)

Install bignumber.js for high‑precision arithmetic and safe conversion.

# Install
npm install bignumber.js

import BigNumber from 'bignumber.js';
const bigId = new BigNumber("1951211313641689089");

// Send
await axios.post('/api/delete', { id: bigId.toString() });

Axios global interceptor with json-bigint

Configure Axios to automatically parse large numbers as strings, eliminating the need for manual conversion.

# Install
npm install json-bigint

import axios from 'axios';
import JSONbig from 'json-bigint';

const api = axios.create({
  transformResponse: [data => {
    try {
      return JSONbig({ storeAsString: true }).parse(data);
    } catch (e) {
      return JSON.parse(data);
    }
  }]
});

export const deleteData = async (id) => {
  return await api.post('/api/delete', { id });
};

export const getDataList = async () => {
  return await api.get('/api/list'); // IDs are already strings
};

4. Best‑practice tips

When dealing with Snowflake IDs, UUIDs, or other long identifiers, always treat them as strings on the front end.

Agree on a transmission format (preferably string) between front‑end and back‑end to avoid implicit conversions.

Configure request libraries (Axios, fetch, etc.) globally to handle big numbers, reducing repetitive code.

If data exists but operations fail, first verify that large numeric fields (IDs, phone numbers) were not truncated during transport.