Hash

You might say

I updated the website, so why does it still show the old content?

A digest computed from content using a specified algorithm, often used to compare files or identify versionsA website build can include a script’s content hash in its filename to distinguish old and new files. The page must also reference the new file to load the update. Different contents can collide, so a hash is not an absolutely unique identifier.

Why the page can stay old after the file changes

Greeting page · release example

Build output · UTF-8, no trailing newlinemessage.d3cc7661.js

const message = "Hello";

First 8 hex digits of SHA-256：d3cc7661

Script reference in the page<script src="message.d3cc7661.js">

Page output · LoadedHello

This example hashes the UTF-8 file contents with SHA-256 and uses only the first 8 hex digits in the filename. The page references this file and displays Hello.

What else can a hash help you check?

Matching and differing digests: With the same algorithm, encoding, and other conditions, identical contents yield identical digests. Different digests show different inputs. Matching digests can still be a collision, especially after truncation. A full SHA-256 hex digest has 64 digits; other algorithms can have different lengths.

Downloads and Git: Compare a download using the same algorithm against a digest from a trusted channel. If both file and comparison value are replaced, a match does not prove authenticity. Git hashes objects; commit contents also include parent commits and commit metadata. A short hash must distinguish the object within the current repository.

Quick checkChoose the best answer

The script filename changed with its contents, but revisiting still shows old text. The page still references the old file. What should you inspect first?

Disable caching for scripts so the browser fetches the referenced file againCheck whether the entry page and its cache still serve the old referenceExtend the new filename hash from 8 digits to the full digest and redeploy

You can say this to an AI Agent

The site still shows old content after deployment. Check content hashes in build output, resource references in the entry page, and caching. Compare filenames before and after the edit, rebuild unchanged content to check hash stability, and verify that revisiting loads the new file.

Related terms

1Build→2Deployment→3Git→

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