Why this doesn't work?

Question

var str="Hello World!"; 
var patt=/\x57/g;
var matched = str.match(patt);
document.write(matched.strike());

It seems that the problem is matched.strike() . With matched only it works. So why?

Answer 1

The .strike() method operates on strings and matched is an array. You must dereference the first match to see the correct output.

var str="Hello World!"; 
var patt=/\x57/g;
var matched = str.match(patt);
// Access first element of the matched array
document.write(matched[0].strike());

// Or via .pop() or .shift()
document.write(matched.pop().strike());
// or
document.write(matched.shift().strike());
// either returns "<strike>W</strike>"

The String.strike() method is nonstandard , and should not be relied upon for complete browser support.

Answer 2

The (very old) strike method is a String method. RegExp.match returns an Array which doesn't know a strike method.

Your code could be rewritten to:

var str = 'Hello World'.replace(/\x57/g,function(s){return s.strike();});
//=> Hello <strike>W</strike>orld