$1...$9 属性 (RegExp) (JavaScript)

var newLine = "<br />";

var re = /(\w+)@(\w+)\.(\w+)/g
var src = "Please send mail to george@contoso.com and someone@example.com. Thanks!"

var result;
var s = "";

// Get the first match.
result = re.exec(src);

while (result != null) {
    // Show the entire match.
    s += newLine;

    // Show the match and submatches from the RegExp global object.
    s += "RegExp.lastMatch: " + RegExp.lastMatch + newLine;
    s += "RegExp.$1: " + RegExp.$1 + newLine;
    s += "RegExp.$2: " + RegExp.$2 + newLine;
    s += "RegExp.$3: " + RegExp.$3 + newLine;

    // Show the match and submatches from the array that is returned
    // by the exec method.
    for (var index = 0; index < result.length; index++) {
        s +=  index + ": ";
        s += result[index];
        s += newLine;
    }

    // Get the next match.
    result = re.exec(src);
}
document.write(s);

// Output:
//  RegExp.lastMatch: george@contoso.com
//  RegExp.$1: george
//  RegExp.$2: contoso
//  RegExp.$3: com
//  0: george@contoso.com
//  1: george
//  2: contoso
//  3: com

//  RegExp.lastMatch: someone@example.com
//  RegExp.$1: someone
//  RegExp.$2: example
//  RegExp.$3: com
//  0: someone@example.com
//  1: someone
//  2: example
//  3: com