Regular-expression match and Exec comparisons

Match and exec differ in two main points:

1.exec is a method of a regular expression, not a method of a string, and its argument is the string, as follows:

var re=New RegExp (/\d/"abc4def" );

Or use the Perl style:

" Abc4def " );

Match is the method provided by the string class, and its arguments are regular expression objects, and the following usage is correct:

" Abc4def ". Match (\d);

Or

" Abc4def ". Match ("ABC");

2.exec and match return all arrays

• The regular expression that executes the Exec method is not grouped, so if there is a match, he will return an array with only one element, or null if there is no match.
• exec does not support I m g

The following two alert functions pop up with the same message:

var " Cat,hat "  ; var // No G attribute Alert (p.exec (str))//["at"]alert (Str.match (P))// ["at"]

Then the exec and match methods are equal

var " Cat,hat "  ; var // Note the G property Alert (p.exec (str))// ["at"]

alert (Str.match (P))// [' at ', ' at ']

Because exec always returns only the first match, and match returns all matches when the G attribute is specified in the regular.

exec if a match is found and contains a grouping , the returned array will contain more than one element, the first element being the match found, followed by the first and second of the matching elements. Group (reverse reference)
The following code will pop up "Cat2,at":

var " cat2,hat8 "  ; var p=/c (at) \d/; alert (p.exec (str))//[' Cat2 ', ' at ']

The match function implements the same functionality as exec when it meets the following conditions: someone else

• 1, the regular expression contains the grouping (parentheses)
• 2, return the only match, do not use g,m time

var " cat2,hat8 "  ; var p=/c (at) \d/; alert (p.exec (str))//[' Cat2 ', ' at ']alert (Str.match (p))//[' Cat2 ', ' at ']

var p=/c (at) \d/g;
Alert (Str.match (p))//["Cat2", "at"]

　　

Regular-expression match and Exec comparisons