Strange behavior javascript regexp

Question

console.log("url/page/value".match(/\/([a-zA-Z0-9]+)/g));

Why this code return an array: [/page, /value]? Why captured symbol '/'?

jsfiddle: http://jsfiddle.net/wq93T/

Thanks in advance.

Answer 1

Because

1. the \\/ in your regex means: match the literal character / (the forward slash has to be escaped by a backslash because it is also the /pattern delimiter/ )
2. the g modifier makes you return all matches

Taken together, the regex \\/([a-zA-Z0-9]+) means:

1. match the literal character /
2. match one or more characters that are letters or digits, capturing them to Group 1.

So this will match /somethingLikeThis

You can see that clearly in this demo , and experiment by adding strings to see what matches, or by editing the regex.

Answer 2

您使用\\转义/尝试使用此方法，即\\/表示/

 console.log("url/page/value".match(/([a-zA-Z0-9]+)/g));

Answer 3

var path = "url/page/value";
var regex = /\/([a-zA-Z0-9]+)/g;
var match = regex.exec(path);
console.log(match[0]); // "/page"
console.log(match[1]); // "page"

match = regex.exec(path);
console.log(match[0]); // "/value"
console.log(match[1]); // "value"

match = regex.exec(path);
console.log(match); //null

JSFiddle

The array returned by exec contains the entire match in index 0, and captures (values in parenthesis) at subsequent indices (first at 1, second at 2, etc).

As a single line:

console.log(/\/([a-zA-Z0-9]+)/g.exec("url/page/value")[1]); // "page"

As a function that returns an array of captures:

var path = "url/page/value";
var regex = /\/([a-zA-Z0-9]+)/g;

console.log(capturedMatch(path, regex, 1));

function capturedMatch(str, rgx, index) {
    var m;
    var res = [];
    while((m = rgx.exec(str)) != null) {
        res.push(m[index]);
    }
    return res;
}

JSFiddle

Answer 4

The expression can be further simplified, if you do not want the / , to:

console.log("url/page/value".match(/[a-zA-Z0-9]+/g));

Or

console.log("url/page/value".match(/[^\/]+/g));

Or

console.log("url/page/value".split('/'));

JS FIDDLE DEMO