LWC越来越便利了，本次更新内容值得一看！

 https://trailhead.salesforce.com/content/learn/modules/javascript-developer-i-certification-maintenance-summer-23 

此维护模块分为两部分，第一部分是选择题，仔细阅读文章后都能答对，所以我直接给出第二部分代码示例，仅供参考。

①.Child LWC （只需要js, 其余默认新建即可）：

import { LightningElement, api } from "lwc";
import LightningAlert from "lightning/alert";
export default class Child extends LightningElement {
      @api
      async sayHi() {
            await LightningAlert.open({
                  message: "Hello Trailblazer!",
                  theme: "success",
                  label: "Greetings"
      });  
        console.log("Alert modal has been closed");
     }
}

②.Parent LWC （需要将本次更新应用到维护模块中的示例代码上）：

import { LightningElement, api, wire } from "lwc";
import { getRecord, getFieldValue } from "lightning/uiRecordApi";
import FIELD_NAME from "@salesforce/schema/Account.Name";
import FIELD_OWNER_NAME from "@salesforce/schema/Account.Owner.Name";
import FIELD_PHONE from "@salesforce/schema/Account.Phone";
import FIELD_INDUSTRY from "@salesforce/schema/Account.Industry";
export default class Parent extends LightningElement {
      @api recordId;
      @wire(getRecord, { recordId: "$recordId", fields: [FIELD_NAME, FIELD_INDUSTRY], optionalFields: [FIELD_PHONE, FIELD_OWNER_NAME] })
account;
      get name() {
            return getFieldValue(this.account.data, FIELD_NAME);
}
      get phone() {
            return getFieldValue(this.account.data, FIELD_PHONE);
}
      get industry() {
            return getFieldValue(this.account.data, FIELD_INDUSTRY);
}
      get owner() {
            return getFieldValue(this.account.data, FIELD_OWNER_NAME);
}
      sayHi() {
            let cmp = this.refs.child; //无需querySelector()即可取得DOM元素
            cmp.sayHi();
     }
}

<template>
    <lightning-card title="Summer '23 Maintenance">
          <lightning-button slot="actions" label="Say Hi" onclick={sayHi}></lightning-button>
          <template lwc:if={account.data}>    <!--取代了原先的if:true-->
                <div class="slds-m-around_medium">
                      <p>Account Name: {name}</p>
                      <p>Industry: {industry}</p>
                      <p>Phone: {phone}</p>
                      <p>Owner: {owner}</p>
               </div>
         </template>
         <template lwc:else>    <!--取代了原先的if:false-->
              <div class="slds-m-around_medium slds-text-color_destructive">An error occurred while retrieving data</div>
         </template>
         <c-child lwc:ref="child"></c-child>    <!--js中的this.refs.child ，就是它-->
   </lightning-card>
</template>

<?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata">
    <apiVersion>58.0</apiVersion>
    <isExposed>true</isExposed>
    <targets>
        <target>lightning__RecordPage</target>
    </targets>
    <targetConfigs>
        <targetConfig targets="lightning__RecordPage">
            <objects>
                <object>Account</object>   <!--指定到Account record页面-->
            </objects>
        </targetConfig>
   </targetConfigs>
</LightningComponentBundle>