The difference explanation of Test,exec,match method in JS regular expression _javascript skill

The difference explanation of Test,exec,match method in JS regular expression

Test
Test returns a Boolean to find out if the pattern exists in the corresponding string.
var str = "1a1b1c";
var reg = new RegExp ("1.", "");
Alert (Reg.test (str)); True

Exec
Exec finds and returns the current matching result, and returns as an array.
var str = "1a1b1c";
var reg = new RegExp ("1.", "");
var arr = reg.exec (str);
If the pattern does not exist, then ARR is null, otherwise arr is always an array of length 1, whose value is the current match. ARR also has three properties: the position of the current match for index, lastindex the position at which the current match ends (index + the length of the current match); input is str in the example above.

The Exec method is affected by the parameter G. If G is specified, the next time you call Exec, the lookup starts with the last matching lastindex.
var str = "1a1b1c";
var reg = new RegExp ("1.", "");
Alert (reg.exec (str) [0]);
Alert (reg.exec (str) [0]);
Both of these outputs are 1a. Now look at the specified parameter g:
var str = "1a1b1c";
var reg = new RegExp ("1.", "G");
Alert (reg.exec (str) [0]);
Alert (reg.exec (str) [0]);
The first output is 1a and the second output is 1b.

Match
Match is a method of a String object.
var str = "1a1b1c";
var reg = new RegExp ("1.", "");
Alert (Str.match (reg));
Match is a bit like exec, but: exec is the way to REGEXP objects; Math is a method of String objects. A different point is the explanation of the parameter G.
If parameter g is specified, match returns all results at once.
var str = "1a1b1c";
var reg = new RegExp ("1.", "G");
Alert (Str.match (reg));
Alert (Str.match (reg)); The result of this sentence is the same
The result is an array of three elements: 1a, 1b, 1c.

Regular expressions are often used in JavaScript, while regular expressions often use the two functions of match and test, and of course exec. Here's a code example to differentiate between them.

Match Example

Copy Code code as follows:

var str = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ";
var regexp =/[a-e]/gi;
var rs = Str.match (regexp);
rs= Array (' A ', ' B ', ' C ', ' D ', ' e ', ' A ', ' B ', ' C ', ' d ', ' e ');

Test Example

Copy Code code as follows:

var str = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ";
var regexp =/[a-e]/gi;
var rs = regexp.test (str);
rs = true; Boolean

exc Example

Copy Code code as follows:

var str = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ";
var regexp =/[a-e]/gi;
var rs;
while (rs = regexp.exec (str))!= null)
{
document.write (RS);
document.write (Regexp.lastindex);
document.write ("<br/>");
}

OUTPUT
---------------------------------
A 1
B 2
C 3
D 4
E 5
A 27
B 28
C 29
D 30
E 31

Another exc Example

Copy Code code as follows:

var regexp =/ab*/g;
var str = "Abbcdefabh";
var rs;
while (rs = regexp.exec (str))!= null)
{
document.write (RS);
document.write (Regexp.lastindex);
document.write ("<br/>");
}

OUTPUT
---------------------------------
ABB 3
AB 9