I noticed in the ECMA 5 draft that String#replace references
String#match's handling of regexp.lastIndex
when the regexp is flagged global. According to the draft String#match
sets the regexp.lastIndex when the regexp is global.
All of this is identical to ECMA-262 Edition 3.
Currently Firefox, Chrome, Safari, Opera do not set the lastIndex on
String#match
Yes they do. Leaving aside whatever happens during the matching process
(since it's unobservable to users), String#match called with a "global"
RegExp always starts searching from index 0 and the RegExp's lastIndex is
always 0 after after the method is complete. (That is, except in IE, which
has the bug you mentioned where lastIndex is not always 0 after a match or
replace using a "global" regex is complete.)
This should alert 0, demonstrating that the browsers you mentioned do update
lastIndex:
var x = /x/g;
x.lastIndex = 1;
"x123x5".match(x);
alert(x.lastIndex);
or String#replace.
IE does set the lastIndex but only once, not during each internal
iteration of `Repeat, while lastMatch is true`, and for non-global
regexp's as well.
According to spec I would expect:
var s = '0x2x4x6x8';
var p = /x/g;
s.replace(p, function() { alert(p.lastIndex) }); // A: alerts 2, then
4, then 6, then 8
alert(p.lastIndex); // B: alerts 0 because internal exec returned null
(which set lastIndex 0) triggering the end of the iteration;
// IE7
// A: alerts 0, then 0, then 0, then 0
// B: alerts 8
// All others
// A: alerts 0, then 0, then 0, then 0
// B: alerts 0
Opera 9.64 (and other versions I've previously tested this issue with)
alerts A: 2, 4, 6, 8 and B: 0. Like you, this is my interpretation of
correct handling according to the spec. Opera tends to follow the spec most
closely for regex issues, in general.
This might be a compatibility issue to consider.
Sure, but it's a decade old.
Steve
--------------------
Steven Levithan
Baghdad, Iraq
http://blog.stevenlevithan.com
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