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Converted to HTML in WebWorks Publisher 2000. manual wdt 1.5"> <META NAME="LASTUPDATED" CONTENT="09/28/00 13:15:05"> <TITLE> Core JavaScript Reference 1.5: About this Book</TITLE></HEAD><BODY TEXT="#000000" LINK="#666699" VLINK="#666699" ALINK="#333366" BGCOLOR="#FFFFFF"><MAINCONTENT><NAVIGATIONCONTENT> <TABLE WIDTH="100%" BORDER="0" CELLSPACING="4"> <TR> <TD VALIGN="TOP"> <b><a href="contents.html"><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2" COLOR="#993300">Previous</a></FONT> </b><a href="contents.html"><b><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2" COLOR="#993300">Contents</a></FONT></b> <a href="ix.html"><b><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2" COLOR="#993300">Index</a></FONT></b> <a href="partobj.html"><b><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2" COLOR="#993300">Next</a></FONT></b> </TD> </TR> <TR> <TD VALIGN="TOP" ALIGN="RIGHT" BGCOLOR="#CCCCCC"> <FONT FACE="Arial, Helvetica, sans-serif" COLOR="#000000" SIZE="2"><B> Core JavaScript Reference 1.5</B></FONT> </TD> </TR> <TR> </TABLE> <BR></NAVIGATIONCONTENT><BOOKCONTENT> <blockquote><BR><BR> <A NAME="1001665"> </A><A NAME="About this Book"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="4" COLOR="#000000"><B><zchaptitle>About this Book</zchaptitle></B></FONT><BR><BR><BR><A NAME="1003098"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>JavaScript is Netscape's cross-platform, object-based scripting language. This book is a reference manual for the core JavaScript language.</zparagraph></FONT><P><A NAME="1001667"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>This preface contains the following sections:</zparagraph></FONT><P><ul><A NAME="1001671"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><A HREF="preface.html#1003152" >New Features in this Release</A></zsmartlist1></FONT><P><A NAME="1003167"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><A HREF="preface.html#1005135" >What You Should Already Know</A></zsmartlist1></FONT><P><A NAME="1003563"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><A HREF="preface.html#1003515" >JavaScript Versions</A></zsmartlist1></FONT><P><A NAME="1001675"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><A HREF="preface.html#1001692" >Where to Find JavaScript Information</A></zsmartlist1></FONT><P><A NAME="1001679"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><A HREF="preface.html#1001745" >Document Conventions</A></zsmartlist1></FONT><P></ul><BR><BR><A NAME="1003152"> </A><A NAME="New Features in this Release"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="4"><zhead1>New Features in this Release</zhead1><HR SIZE="2" NOSHADE></FONT><BR><A NAME="1004963"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>JavaScript version 1.5 provides the following new features and enhancements:</zparagraph></FONT><P><ul><A NAME="1004964"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><B>Runtime errors.</B> Runtime errors are now reported as exceptions.</zsmartlist1></FONT><P><A NAME="1004965"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><B>Number formatting enhancements.</B> Number formatting has been enhanced to include <FONT FACE="courier, couriernew, monospaced size">Number.prototype.toExponential</FONT>, <FONT FACE="courier, couriernew, monospaced size">Number.protoytpe.toFixed</FONT> and <FONT FACE="courier, couriernew, monospaced size">Number.prototype.toPrecision</FONT> methods. See <A HREF="number.html#1200968" >page 127</A>, <A HREF="number.html#1200964" >page 128</A>, and <A HREF="number.html#1201389" >page 129</A>.</zsmartlist1></FONT><P><A NAME="1004975"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><B>Regular expression enhancements:</B> </zsmartlist1></FONT><P> <ul><A NAME="1004976"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist2>Greedy quantifiers — <FONT FACE="courier, couriernew, monospaced size">+</FONT>, <FONT FACE="courier, couriernew, monospaced size">*</FONT>, <FONT FACE="courier, couriernew, monospaced size">?</FONT> and <FONT FACE="courier, couriernew, monospaced size">{} </FONT>— can now be followed by a <FONT FACE="courier, couriernew, monospaced size">?</FONT> to force them to be non-greedy. See the entry for <FONT FACE="courier, couriernew, monospaced size">?</FONT> on <A HREF="regexp.html#1193226" >page 148</A>.</zsmartlist2></FONT><P><A NAME="1004980"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist2>Non-capturing parentheses, <FONT FACE="courier, couriernew, monospaced size">(?:x)</FONT> can be used instead of capturing parentheses<FONT FACE="courier, couriernew, monospaced size">(x)</FONT>. When non-capturing parentheses are used, matched subexpressions are not available as back-references. See the entry for <FONT FACE="courier, couriernew, monospaced size">(?:x)</FONT> on <A HREF="regexp.html#1207798" >page 148</A>.</zsmartlist2></FONT><P><A NAME="1004984"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist2><FONT FACE="courier, couriernew, monospaced size">P</FONT>ositive and negative lookahead assertions are supported. Both assert a match depending on what follows the string being matched. See the entries for <FONT FACE="courier, couriernew, monospaced size">(?=)</FONT> and <FONT FACE="courier, couriernew, monospaced size">(?!)</FONT> on <A HREF="regexp.html#1207831" >page 148</A>.</zsmartlist2></FONT><P><A NAME="1004988"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist2>The <FONT FACE="courier, couriernew, monospaced size">m</FONT> flag has been added to specify that the regular expression should match over multiple lines. See <A HREF="regexp.html#1193159" >page 146</A>.</zsmartlist2></FONT><P> </ul><A NAME="1004995"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><B>Conditional function declarations.</B> Functions can now be declared inside an <FONT FACE="courier, couriernew, monospaced size"><B>if</B></FONT> clause. See <A HREF="stmt.html#1076846" >page 221</A>.</zsmartlist1></FONT><P><A NAME="1005213"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><B>Function expressions.</B> Functions can now be declared inside an expression. See <A HREF="ops.html#1066344" >page 254</A>.</zsmartlist1></FONT><P><A NAME="1004999"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><B>Multiple </B><FONT FACE="courier, couriernew, monospaced size"><B>catch</B></FONT><B> clauses. </B>Multiple <FONT FACE="courier, couriernew, monospaced size">catch</FONT> clauses in a <FONT FACE="courier, couriernew, monospaced size">try...catch</FONT> statement are supported. See <A HREF="stmt.html#1079200" >page 231</A>.</zsmartlist1></FONT><P><A NAME="1005131"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><B>Constants.</B> Readonly, named constants are supported. This feature is available only in the C implementation of JavaScript. See <A HREF="stmt.html#1077887" >page 215</A>.</zsmartlist1></FONT><P><A NAME="1005132"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1><B>Getters and Setters.</B> JavaScript writers can now add getters and setters to their objects. This feature is available only in the C implementation of JavaScript. See Defining Getters and Setters in Chapter 7 of the <I>Core JavaScript Guide</I> for information about this feature.</zsmartlist1></FONT><P></ul><BR><BR><A NAME="1005135"> </A><A NAME="What You Should Already Know"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="4"><zhead1>What You Should Already Know</zhead1><HR SIZE="2" NOSHADE></FONT><BR><A NAME="1003432"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>This book assumes you have the following basic background:</zparagraph></FONT><P><ul><A NAME="1003190"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1>A general understanding of the Internet and the World Wide Web (WWW).</zsmartlist1></FONT><P><A NAME="1003191"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B> <li></B><zsmartlist1>Good working knowledge of HyperText Markup Language (HTML).</zsmartlist1></FONT><P></ul><A NAME="1003192"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Some programming experience with a language such as C or Visual Basic is useful, but not required.</zparagraph></FONT><P><BR><BR><A NAME="1003515"> </A><A NAME="JavaScript Versions"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="4"><zhead1>JavaScript Versions</zhead1><HR SIZE="2" NOSHADE></FONT><BR><A NAME="1003516"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>Each version of Navigator supports a different version of JavaScript. To help you write scripts that are compatible with multiple versions of Navigator, this manual lists the JavaScript version in which each feature was implemented.</zparagraph></FONT><P><A NAME="1003517"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><zparagraph>The following table lists the JavaScript version supported by different Navigator versions. Versions of Navigator prior to 2.0 do not support JavaScript.</zparagraph></FONT><P><P><A NAME="1003548"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><BR><P><TABLE WIDTH="90%" BORDER="1" CELLPADDING="5" CELLSPACING="0"> <CAPTION></CAPTION><P><FONT FACE=""><B><A NAME="1003521"> </A><A NAME="JavaScript and Navigator versions"> </A><ALIGN="LEFT"><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><ztablecaptionp>Table 1    JavaScript and Navigator versions</ztablecaptionp></B></FONT></B></FONT><BR><BR> <TR BGCOLOR="#CCCCCC" ALIGN=LEFT VALIGN=TOP> <TH VALIGN=TOP ALIGN=LEFT><A NAME="1003525"> </A><P ALIGN="LEFT"><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><ztablehead>JavaScript version</ztablehead></B></FONT></TH> <TH VALIGN=TOP ALIGN=LEFT><A NAME="1003527"> </A><P ALIGN="LEFT"><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><B><ztablehead>Navigator version</ztablehead></B></FONT></TH> </DIV></TR> <TR> <TD VALIGN=TOP><P><A NAME="1003529"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>JavaScript 1.0</ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1003531"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>Navigator 2.0</ztabletext></FONT> </TD> </TR> <TR> <TD VALIGN=TOP><P><A NAME="1003533"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>JavaScript 1.1</ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1003535"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>Navigator 3.0</ztabletext></FONT> </TD> </TR> <TR> <TD VALIGN=TOP><P><A NAME="1003537"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>JavaScript 1.2</ztabletext></FONT> </TD> <TD VALIGN=TOP><P><A NAME="1003539"> </A><FONT FACE="Arial, Helvetica, sans-serif" SIZE="2"><ztabletext>Navigator 4.0-4.05</ztabletext></FONT> </TD> </TR>⌨️ 快捷键说明
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