Method insertBefore

packages/miniprogram-render/src/node/element.js:844–889

(node, ref)

    }

    insertBefore(node, ref) {
        if (!(node instanceof Node)) return
        if (ref && !(ref instanceof Node)) return

        let nodes
        let hasUpdate = false

        if (node.nodeType === Node.DOCUMENT_FRAGMENT_NODE) {
            // documentFragment
            nodes = []
            for (let i = 0; i < node.childNodes.length; i++) {
                // 因为是逐个插入，所以需要逆序
                nodes.push(node.childNodes[i])
            }
        } else {
            nodes = [node]
        }

        for (const node of nodes) {
            if (node === this) continue
            if (node.parentNode) node.parentNode.removeChild(node)

            const insertIndex = ref ? this.$_children.indexOf(ref) : -1

            if (insertIndex === -1) {
                // 插入到末尾
                this.$_children.push(node)
            } else {
                // 插入到 ref 之前
                this.$_children.splice(insertIndex, 0, node)
            }

            node.$$updateParent(this) // 设置 parentNode

            // 更新映射表
            this.$_updateChildrenExtra(node)

            hasUpdate = true
        }


        // 触发 webview 端更新
        if (hasUpdate) this.$_triggerMeUpdate()

        return node
    }

    replaceChild(node, old) {
        if (!(node instanceof Node) || !(old instanceof Node)) return