[TOC] ***** ## 2 optimizer.js ast優化 >[info] import ~~~ ;(導入)基礎工具 import { makeMap, isBuiltInTag } from 'shared/util' ~~~ >[info] module ~~~ ;平臺保留標簽 let isPlatformReservedTag ;解析結果優化 export function optimize (root, options) { ;是否平臺保留標簽 isPlatformReservedTag = options.isReservedTag || (() => false) ;第一次遍歷 markStatic(root) ;第二次遍歷 markStaticRoots(root) } ;第一次遍歷 標記所有非靜態節點 function markStatic (node) { node.static = isStatic(node) if (node.children) { for (let i = 0, l = node.children.length; i < l; i++) { const child = node.children[i] markStatic(child) if (!child.static) { node.static = false } } } } ;第二次遍歷 標記所有靜態節點 function markStaticRoots (node) { if (node.tag && (node.once || node.static)) { node.staticRoot = true return } if (node.children) { for (let i = 0, l = node.children.length; i < l; i++) { markStaticRoots(node.children[i]) } } } ;靜態屬性key const isStaticKey = makeMap( 'tag,attrsList,attrsMap,plain,parent,children,' + 'staticAttrs,staticClass' ) ;靜態屬性檢測 function isStatic (node) { return !!(node.text || node.pre || ( !node.expression && // not text with interpolation !node.if && !node.for && // not v-if or v-for or v-else (!node.tag || isPlatformReservedTag(node.tag)) && // not a component !isBuiltInTag(node.tag) && // not a built-in (node.plain || Object.keys(node).every(isStaticKey)) // no dynamic bindings )) } ~~~ >[info] export ~~~ ;(導出)解析結果優化 export function optimize (root, options) { ~~~