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2010-05-26T10:02:39Z

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==A Custom Object Exception==



<source lang="html4strict">
/*
JavaScript Bible, Fourth Edition
by Danny Goodman
John Wiley & Sons CopyRight 2001
*/

<HTML>
<HEAD>
<TITLE>Throwing a Custom Error Object Exception</TITLE>
<SCRIPT LANGUAGE="JavaScript">
var letters = new Array("A","B","C","D","E")
function getErrorObj(msg) {
var err = new Error(msg)
// take care of IE5/5.5
if (!err.message) {
err.message = msg
}
err.name = "MY_ERROR"
return err
}
function getLetter(fld) {
try {
var inp = parseInt(fld.value, 10)
if (isNaN(inp)) {
throw getErrorObj("Entry was not a number.")
}
if (inp < 1 || inp > 5) {
throw getErrorObj("Enter only 1 through 5.")
}
fld.form.output.value = letters[inp]
}
catch (e) {
switch (e.name) {
case "MY_ERROR" :
alert(e.message)
fld.form.output.value = ""
fld.focus()
fld.select()
break
default :
alert("Reload the page and try again.")
}
}
}
</SCRIPT>
</HEAD>
<BODY>
<H1>Throwing a Custom Error Object Exception</H1>
<HR>
<FORM>
Enter a number from 1 to 5:
<INPUT TYPE="text" NAME="input" SIZE=5>
<INPUT TYPE="button" VALUE="Get Letter" onClick=getLetter(this.form.input)>
Matching Letter is:<INPUT TYPE="text" NAME="output" SIZE=5>
</FORM>
</BODY>
</HTML>

</source>

==An Exception Handling Example==



<source lang="html4strict">
<HTML>
<HEAD><TITLE>Exception Test</TITLE></HEAD>
<SCRIPT LANGUAGE="JavaScript"></SCRIPT>
<BODY>
<P>This script only works with Internet Explorer 5, Navigator 6, or later browsers.</P>
<SCRIPT LANGUAGE="JavaScript"></SCRIPT>
</BODY>
</HTML>

</source>

==Catching an Error==



<source lang="html4strict">
<HTML>
<TITLE>Catch that error!</TITLE>
<SCRIPT>
function catchError(errString) {
try {
try {
if (errString == 42)
throw new Error (42, "errString is 42 !");
else
throw new Error (0, "errString is NOT 42 !");
}
catch(e) {
if (e.number == 42)
return (e.description + " Got this one!");
else
throw e; // re-throw the error
}
}
catch (e){
return(e.description + " This one not handled here!");
}
}
</SCRIPT>
</HEAD>
<BODY>
<H1>
Catch that error!
</H1>
<FORM name="theForm">
<TABLE>
<TR><TD colspan=2> We can handle 42: </TD><TD><INPUT type=text name=errText size=40 value="42"></TD></TR>
<TR><TD colspan=2></TD>
<TD><INPUT type=button name=btnThrow value="Catch it!" onClick="alert(catchError(document.theForm.errText.value));">
</TD>
</TR>
</TABLE>
</FORM>
</BODY>
</HTML>

</source>

==Catching the "Object Expected" Error==



<source lang="html4strict">
<HTML>
<BODY>
<H1>
<SCRIPT>
function dosomething() {
}
function goodFunc(){
try {
doSomething();
}
catch (e) {
if (e.description == "Object expected") {
alert("Cannot find a function named doSomething!");
}
else {
alert ("Other error" + e.description);
}
}
}
</SCRIPT>
</H1>
<FORM>
<INPUT type=button value="Click" onClick="goodFunc();">
</FORM>
</BODY>
</HTML>

</source>

==Controlling Script Errors==



<source lang="html4strict">
/*
JavaScript Bible, Fourth Edition
by Danny Goodman
John Wiley & Sons CopyRight 2001
*/

<HTML>
<TITLE>Error Dialog Control</TITLE>
<SCRIPT LANGUAGE="JavaScript1.1">
// function with invalid variable value
function goWrong() {
var x = fred
}
// turn off error dialogs
function errOff() {
window.onerror = doNothing
}
// turn on error dialogs with hard reload
function errOn() {
window.onerror = handleError
}
// assign default error handler
window.onerror = handleError
// error handler when errors are turned off...prevents error dialog
function doNothing() {return true}
function handleError(msg, URL, lineNum) {
var errWind = window.open("","errors","HEIGHT=270,WIDTH=400")
var wintxt = "<HTML><BODY BGCOLOR=RED>"
wintxt += "<B>An error has occurred on this page. "
wintxt += "Please report it to Tech Support.</B>"
wintxt += "<FORM METHOD=POST ENCTYPE="text/plain" "
wintxt += "ACTION=mailTo:support4@dannyg.ru >"
wintxt += "<TEXTAREA NAME="errMsg" COLS=45 ROWS=8 WRAP=VIRTUAL>"
wintxt += "Error: " + msg + "\n"
wintxt += "URL: " + URL + "\n"
wintxt += "Line: " + lineNum + "\n"
wintxt += "Client: " + navigator.userAgent + "\n"
wintxt += "-----------------------------------------\n"
wintxt += "Please describe what you were doing when the error occurred:"
wintxt += "</TEXTAREA><P>"
wintxt += "<INPUT TYPE=SUBMIT VALUE="Send Error Report">"
wintxt += "<INPUT TYPE=button VALUE="Close" onClick="self.close()">"
wintxt += "</FORM></BODY></HTML>"
errWind.document.write(wintxt)
errWind.document.close()
return true
}
</SCRIPT>
</HEAD>
<BODY>
<FORM NAME="myform">
<INPUT TYPE="button" VALUE="Cause an Error" onClick="goWrong()"><P>
<INPUT TYPE="button" VALUE="Turn Off Error Dialogs" onClick="errOff()">
<INPUT TYPE="button" VALUE="Turn On Error Dialogs" onClick="errOn()">
</FORM>
</BODY>
</HTML>

</source>

==Nested Exception Handling (This script only works with Internet Explorer 5, Navigator 6, or later browsers)==



<source lang="html4strict">

<HTML>
<HEAD><TITLE>Exception Test</TITLE></HEAD>
<SCRIPT LANGUAGE="JavaScript"></SCRIPT>
<BODY>
<SCRIPT LANGUAGE="JavaScript"></SCRIPT>
</BODY>
</HTML>

</source>

==Throwing an Error==



<source lang="html4strict">
<HTML>
<HEAD>
<TITLE>Throw that error!</TITLE>
<SCRIPT>
function throwError(errString) {
try {
throw new Error (42, errString);
}
catch(e){
alert("Error number: " + e.number + "; Description: " + e.description)
}
}
</SCRIPT>
</HEAD>
<BODY>
<H1>
Throw that error!
</H1>
<FORM name="theForm">
<TABLE>
<TR>
<TD colspan=2> Enter text for the error: </TD>
<TD>
<INPUT type=text name=errText size=40>
</TD>
</TR>
<TR>
<TD colspan=2>
</TD>
<TD>
<INPUT type=button name=btnThrow value="Throw it!" onClick="throwError(document.theForm.errText.value);">
</TD>
</TR>
</TABLE>
</FORM>
</BODY>
</HTML>

</source>

==Throwing an Error Object Exception==



<source lang="html4strict">
/*
JavaScript Bible, Fourth Edition
by Danny Goodman
John Wiley & Sons CopyRight 2001
*/

<HTML>
<HEAD>
<TITLE>Throwing an Error Object Exception</TITLE>
<SCRIPT LANGUAGE="JavaScript">
var letters = new Array("A","B","C","D","E")
function getErrorObj(msg) {
var err = new Error(msg)
// take care of IE5/5.5
if (!err.message) {
err.message = msg
}
return err
}
function getLetter(fld) {
try {
var inp = parseInt(fld.value, 10)
if (isNaN(inp)) {
throw getErrorObj("Entry was not a number.")
}
if (inp < 1 || inp > 5) {
throw getErrorObj("Enter only 1 through 5.")
}
fld.form.output.value = letters[inp]
}
catch (e) {
alert(e.message)
fld.form.output.value = ""
fld.focus()
fld.select()
}
}
</SCRIPT>
</HEAD>
<BODY>
<H1>Throwing an Error Object Exception</H1>
<HR>
<FORM>
Enter a number from 1 to 5:
<INPUT TYPE="text" NAME="input" SIZE=5>
<INPUT TYPE="button" VALUE="Get Letter" onClick=getLetter(this.form.input)>
Matching Letter is:<INPUT TYPE="text" NAME="output" SIZE=5>
</FORM>
</BODY>
</HTML>

</source>

== Throwing String Exceptions==



<source lang="html4strict">
<HTML>
<HEAD>
<TITLE>Throwing a String Exception</TITLE>
<SCRIPT LANGUAGE="JavaScript">
var letters = new Array("A","B","C","D","E")
function getLetter(fld) {
try {
var inp = parseInt(fld.value, 10)
if (isNaN(inp)) {
throw "Entry was not a number."
}
if (inp < 1 || inp > 5) {
throw "Enter only 1 through 5."
}
fld.form.output.value = letters[inp-1]
}
catch (e) {
alert(e)
fld.form.output.value = ""
fld.focus()
fld.select()
}
}
</SCRIPT>
</HEAD>
<BODY>
<H1>Throwing a String Exception</H1>
<HR>
<FORM>
Enter a number from 1 to 5:
<INPUT TYPE="text" NAME="input" SIZE=5>
<INPUT TYPE="button" VALUE="Get Letter" onClick=getLetter(this.form.input)>
Matching Letter is:<INPUT TYPE="text" NAME="output" SIZE=5>
</FORM>
</BODY>
</HTML>

</source>

==Using the onError Event Handler==



<source lang="html4strict">

<HTML>
<HEAD>
<TITLE>Handling Errors with onError</TITLE>
<SCRIPT></SCRIPT>
</HEAD>
<BODY>
<H1>Handling Errors with onError</H1>
<FORM>
<INPUT TYPE="BUTTON" ONCLICK="createAnError()"
VALUE="Click here to generate an error.">
</FORM>
</BODY>
</HTML>

</source>

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в 10:02, 26 мая 2010

Admin: 1 версия