patchElement

As explained in Build a Frontend Web Framework (From Scratch)

patchElement is a book-specific function that updates an existing DOM element to match an element virtual node.

patchElement updates an existing DOM element from an old and new element virtual node. It delegates attributes, CSS classes, styles, and event handlers to specialized patching functions; child nodes are handled separately. section 8.2.5

Core implementation shape

const el = oldVdom.el patchAttrs(el, oldAttrs, newAttrs) patchClasses(el, oldClass, newClass) patchStyles(el, oldStyle, newStyle) newVdom.listeners = patchEvents(el, oldListeners, oldEvents, newEvents)

Figure 8.13 Patching an element node

Use the flow diagram to follow element-node patching before examining each delegated operation. section 8.2.5

How Build a Frontend Web Framework (From Scratch) covers it

How deep it goes

Decomposes attributes, classes, styles, and events into implementations, while deferring child-node patching.

Examples

Uses JavaScript listings for delegated patching, attribute diffs, class-list diffs, style diffs, and event-listener replacement.

What it assumes

Assumes old and new virtual nodes, DOM elements, and reconciliation flow; teaches the element-patching decomposition.

What you can do after

Build it from scratch by decomposing element updates into specialized JavaScript patching functions.

How it connects

Connects virtual DOM reconciliation with DOM attributes, CSS classes, styles, event listeners, and fragment nodes.

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This explainer was generated by Manning's knowledge graph from the text of Build a Frontend Web Framework (From Scratch). The section links point to the parts of the book it draws on.