v1/dom/virtual

VirtualList struct

VirtualList is a placeholder that does nothing on non-JS/WASM platforms.

Methods:

{}

{
	height := v.Container.Get("clientHeight").Int()
	scrollTop := v.Container.Get("scrollTop").Int()
	start := max(0, scrollTop/v.ItemHeight)
	end := min(v.Total, start+height/v.ItemHeight+1)

	offsetTop := start * v.ItemHeight
	html := fmt.Sprintf("<div style='height:%dpx'></div>", offsetTop)
	for i := start; i < end; i++ {
		html += v.Render(i)
	}
	offsetBottom := (v.Total - end) * v.ItemHeight
	html += fmt.Sprintf("<div style='height:%dpx'></div>", offsetBottom)
	v.Container.SetHTML(html)
}

{
	if v.stopScroll != nil {
		v.stopScroll()
	}
}

NewVirtualList function

NewVirtualList returns an empty VirtualList placeholder.

Parameters:

• _ string
• _ int
• _ int
• _ func(int) string

Returns:

• *VirtualList

{
	return &VirtualList{}
}

TestVirtualListStub function

TestVirtualListStub ensures the stub implementation is non-nil and callable.

Parameters:

• t *testing.T

{
	v := NewVirtualList("id", 10, 20, func(i int) string { return "" })
	if v == nil {
		t.Fatalf("expected VirtualList instance")
	}
	// Destroy should be a no-op and must not panic.
	v.Destroy()
}

VirtualList struct

VirtualList renders only the portion of a list that is visible within its container.

Fields:

• Container (dom.Element)
• Total (int)
• ItemHeight (int)
• Render (func(i int) string)
• stopScroll (func())

Methods:

{}

{
	height := v.Container.Get("clientHeight").Int()
	scrollTop := v.Container.Get("scrollTop").Int()
	start := max(0, scrollTop/v.ItemHeight)
	end := min(v.Total, start+height/v.ItemHeight+1)

	offsetTop := start * v.ItemHeight
	html := fmt.Sprintf("<div style='height:%dpx'></div>", offsetTop)
	for i := start; i < end; i++ {
		html += v.Render(i)
	}
	offsetBottom := (v.Total - end) * v.ItemHeight
	html += fmt.Sprintf("<div style='height:%dpx'></div>", offsetBottom)
	v.Container.SetHTML(html)
}

{
	if v.stopScroll != nil {
		v.stopScroll()
	}
}

NewVirtualList function

NewVirtualList attaches a virtualized list to the element with the given id.

Parameters:

• containerID string
• total int
• itemHeight int
• render func(i int) string

Returns:

• *VirtualList

{
	v := &VirtualList{
		Container:  dom.Doc().ByID(containerID),
		Total:      total,
		ItemHeight: itemHeight,
		Render:     render,
	}
	v.stopScroll = events.OnScroll(v.Container.Value, func(js.Value) {
		v.update()
	})
	v.update()
	return v
}

testing import

Import example:

import "testing"

fmt import

Import example:

import "fmt"

github.com/rfwlab/rfw/v1/dom import

Import example:

import "github.com/rfwlab/rfw/v1/dom"

github.com/rfwlab/rfw/v1/events import

Import example:

import "github.com/rfwlab/rfw/v1/events"

github.com/rfwlab/rfw/v1/js import

Import example:

import "github.com/rfwlab/rfw/v1/js"

Imported as:

js