The Principles Behind Front-End QR Code Login
This article explains the underlying mechanism of front‑end QR‑code login, detailing the roles of the PC page, mobile device, and server, and walks through the step‑by‑step process from generating the QR code to confirming login and issuing a token.
When browsing PC web pages, users often encounter QR‑code login scenarios. While the feature is familiar, the underlying principle—such as how WeChat or other services implement QR‑code authentication—is not always clear.
The typical user flow includes displaying a QR code on the PC, scanning it with a mobile device, awaiting confirmation, and finally confirming the login to complete the process.
Three key participants are involved: the PC client, the mobile client, and the server. The server coordinates the generation of the QR code, tracks its status, and issues the authentication token after confirmation.
Detailed process steps: ① The PC sends a request to generate a QR code, including device information. ② The server creates a QR‑code ID (bound to the device) and a QR‑code image. ③ The QR‑code ID and image are returned to the PC. ④ The PC displays the QR‑code. ⑤ The PC polls the QR‑code status (via polling, WebSocket, or long‑polling) until it is scanned or expires. ⑥ The mobile device scans the QR‑code and obtains the QR‑code ID. ⑦ The mobile sends its identity information together with the QR‑code ID to the server. ⑧ The server marks the QR‑code as “scanned”. ⑨ The server marks the QR‑code as “awaiting confirmation”. ⑩ The PC receives the “awaiting confirmation” status. ⑪ The user confirms the login on the mobile device. ⑫ The server marks the QR‑code as “confirmed” and generates an authentication token. ⑬ The token is returned to the PC. ⑭ The PC completes the login, and the user is authenticated.
The article also includes promotional links to other technical resources and invites readers to join the official WeChat community for further interaction.
TAL Education Technology
TAL Education is a technology-driven education company committed to the mission of 'making education better through love and technology'. The TAL technology team has always been dedicated to educational technology research and innovation. This is the external platform of the TAL technology team, sharing weekly curated technical articles and recruitment information.
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