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◆ AI Learning · Hard rule

Why does a layout shift reappear after a pane closes, even after a fix?

A timer or interval started inside a pane must be cancelled when the pane closes. The timer must also be cancelled before new timers start in the same pane. This prevents hidden operations that cause layout problems.

By Pawan Nayar · from the LLOS AI Learning record

The rule

A timer or interval started inside a pane must be cancelled when the pane closes.

The timer must also be cancelled before new timers start in the same pane. This prevents hidden operations that cause layout problems.

Timers started inside a pane can keep running after the pane closes. These timers perform operations on the hidden pane's elements. These hidden operations can cause visible layout shifts in other open panes. The original fix might not have stopped these timers.

A developer creates a pane with an animation that uses a timer. The animation shows cards appearing one by one. When the user closes the pane, the developer thinks the animation stops. But the timer keeps running in the background. This causes other parts of the application to move unexpectedly.

Words you'll need

Resolved from this lesson's own record — real definitions, not invented for this page.

Resource Management

Deciding what computing power the AI actually needs

Software Architecture

The blueprint for how a program is organized and built

Questions people ask

More from the same record, pulled by shared topic — not written new for this page.

How can a developer build a mobile view for a web application without breaking the desktop view?

A developer must treat mobile and desktop as two separate apps. They should use media queries to define distinct CSS layouts for each.

What are important ID names for parts of a web page?

A developer uses `#interactive-svg-demo` for the main section that holds an SVG image. JavaScript code will interact with this section.

Why does a web page element disappear when an AI model updates content?

A developer might use `innerHTML` to update a part of a web page. This method replaces all content inside a specific area.

How does the AI tutor tool work?

The AI tutor tool uses a plugin. This plugin includes a CSS file for styling.

What to remember

A timer or interval started inside a pane must be cancelled when the pane closes. The timer must also be cancelled before new timers start in the same pane. This prevents hidden operations that cause layout problems.