johanafm
05-15-2009, 10:05 AM
When declaring variables of local scope to hold regexp objects with /g modifier, I get unexpected results. I see them as a bug, but on the other hand both Safari and FF have similar behaviour, so perhaps I'm missing something.
Every odd call to a function with local variables holding regexp objects will match, and every even call to that same function will fail the match and return null. Unless you set regexpVariable.lastIndex to 0 after declaring the variable.
Yet, with local scope that should not be necessary.
Full code shown below to illustrate the issue. Please enlighten me, because I seriously don't get this behaviour.
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="pragma" content="no-cache" />
<meta http-equiv="cache-control" content="no-cache" />
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>Test</title>
<script type="text/javascript">
var times = 1;
function test() {
// Should yield the same result on every function call, shouldn't it?
var re = /pattern/g;
var ma = re.exec("string pattern");
alert(ma);
// This, however does yield the same result on every call
var reg = /pattern/g;
reg.lastIndex = 0;
var mat = reg.exec("string pattern");
alert(mat);
// And finally, let's make sure a variable holds something other than a regexp object
var rexp = /pattern/g;
var match = rexp.exec("string pattern");
alert(match);
rexp = new String();
// try calling rexp.exec() here. Won't work: rexp.exec is not a function (since rexp is now a string object, not a regexp object. And still, every other call to rexp.exec() fails.
}
</script>
</head>
<body style="margin: 50px;">
<input type="button" onclick="test()" value="test"/>
</body>
</html>
Every odd call to a function with local variables holding regexp objects will match, and every even call to that same function will fail the match and return null. Unless you set regexpVariable.lastIndex to 0 after declaring the variable.
Yet, with local scope that should not be necessary.
Full code shown below to illustrate the issue. Please enlighten me, because I seriously don't get this behaviour.
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="pragma" content="no-cache" />
<meta http-equiv="cache-control" content="no-cache" />
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>Test</title>
<script type="text/javascript">
var times = 1;
function test() {
// Should yield the same result on every function call, shouldn't it?
var re = /pattern/g;
var ma = re.exec("string pattern");
alert(ma);
// This, however does yield the same result on every call
var reg = /pattern/g;
reg.lastIndex = 0;
var mat = reg.exec("string pattern");
alert(mat);
// And finally, let's make sure a variable holds something other than a regexp object
var rexp = /pattern/g;
var match = rexp.exec("string pattern");
alert(match);
rexp = new String();
// try calling rexp.exec() here. Won't work: rexp.exec is not a function (since rexp is now a string object, not a regexp object. And still, every other call to rexp.exec() fails.
}
</script>
</head>
<body style="margin: 50px;">
<input type="button" onclick="test()" value="test"/>
</body>
</html>