JAVASCRIPT语言JAVASCRIPT1.JAVASCRIPT语言简介JavaScript语言背景基本工作方式主要能力无能为力之处ECMAScript代码在HTML文本中引入JavaScript程序的两种方式JavaScript格式1(写在<script>中)<scripttype="text/javascript">//<scriptlanguage="javascript"><!--......--></script>JavaScript格式2(写在<script>中)<scriptsrc="xxx.js"></script>JavaScript格式3<inputtype="checkbox"name="opt"onclick="...;...;...;">JavaScript格式4<inputtype="checkbox"name="opt"><scriptfor="opt"event="onclick"><!--......--></script>对话框和消息框对象对象属性和方法例信息交互JAVASCRIPT变量声明及类型类型转换函数定义函数函数调用表达式与运算符选择if(a>10)a=100;elsea=20;a=((a>10)?100:20);switch(carColour){case"black":document.write(“<p>YouhaveablackMercedes.</p>”);break;case"purlpe":document.write("<p>You…….</p>”);break;default:document.write("<p>……</p>");}循环varcount;for(count=10;count>0;count--)document.write("",count,"");breakcontinuefor(i=0;i<10;i++){document.write("",i,"");if(i<5)break;}for(i=0;i<10;i++){document.write(“”,i,“");if(i<5)continue;}事件(event)及其处理函数和事件属性结合JavaScript事件的分类与表单(FORM)及其元素有关的事件ECMA核心对象集创建对象日期对象Date日期方法<scriptlanguage="JavaScript"><!--now=newDate();document.write(“时间:"+now.getHours()+":"+now.getMinutes()+"<br>");document.write(“日期:"+(now.getMonth()+1)+"/"+now.getDate()+"/"+now.getYear());//--></script>例日期字符串对象String字符串字符的length属性字符串的方法//string.charAt()//ReturnsthecharacteratthespecifiedindexfunctioncharAtTest(n){varstr="ABCDEFGHIJKLMNOPQRSTUVWXYZ";vars;s=str.charAt(n-1);//Getcorrectcharacter//frompositionn–1.return(s);}document.write("charAt(3)",charAtTest(3),"<br>");//string.charCodeAt()//ReturnsanintegerrepresentingtheUnicodeencodingofthe//characteratthespecifiedlocationfunctioncharCodeAtTest(n){varstr="ABCDEFGHIJKLMNOPQRSTUVWXYZ";varn;n=str.charCodeAt(n-1);//GettheUnicodevalueofthe//characteratpositionn.return(n);}document.write("charCodeAt(3)",charCodeAtTest(3),"<br>");//string.concat()functionconcatDemo(){varstr1="ABCDEFGHIJKLM"varstr2="NOPQRSTUVWXYZ";vars=str1.concat(str2);return(s);//s=="ABCDEFGH