substring/regex to get a src value held in a string

Question

I have a string with the value:

var string = \"
Some plain text


        

Answer 1

One approach, is the following:

var string = "
Some plain text
http://www.google.com",
    srcWithQuotes = string.match(/src\=([^\s]*)\s/)[1],
    src = srcWithQuotes.substring(1,srcWithQuotes.length - 1);
console.log(src);​

JS Fiddle demo.

This effectively matches a sequence of characters starting with src= (the = is escaped with a back-slash because, otherwise, it holds special meaning within regular expressions), followed by a sequence of non-white-space characters (^\s*) followed by a white-space character (\s).

This expression explicitly captures the quotes used to delimit the src attribute, the src is returned by taking a substring of the srcWithQuotes variable, starting at 1 (the first, the zeroeth, character should be the attribute delimiter) until the index before the last character (the final quote delimiting the attribute).

There is a slightly convoluted (but potentially more reliable) approach, using a document fragment:

var string = "
Some plain text
http://www.google.com",
    temp = document.createElement('div'),
    frag = document.createDocumentFragment();

temp.innerHTML = string;
frag.appendChild(temp);
console.log(temp.getElementsByTagName('img')[0].src);​​​​​​

JS Fiddle demo.

Of course, in this example, you could use any approach you like to find the image within the temp node (getElementById(), getElementsByClassName()...).