String Parser

Astro-Boy · 07-23-2002, 03:25 AM

Code:

function qq(str) {
  while (str.indexOf('$') != -1) {
    str = str.replace(/\$[^\s\W]+/,eval(str.match(/\$([^\s\W]+)/,"$1")[1]));
  }
  return str;
}

Usage:
var greet = 'hello'; var name = 'john';
alert(qq('$greet there $name!'));

Not overly useful, I just hate having to 'string '+var+' more strings' all the time :P

There are some limitations (vars must be global, etc), but maybe someone will find it helpful. I certainly have

- Mark

Cloudski · 07-23-2002, 05:26 AM

Well, it is interesting to say the least... nice work...

Roy Sinclair · 07-24-2002, 12:56 AM

Quote:

There are some limitations (vars must be global, etc), but maybe someone will find it helpful. I certainly have

There is a way to make local variables and still use your function:

Code:

<html>
    <head>
        <title>Testing</title>
        <script type="text/javascript">
            function qq(str)
                {
                while (str.indexOf('$') != -1)
                    {
                    str = str.replace(/\$[^\s\W]+/,eval(str.match(/\$([^\s\W]+)/,"$1")[1]));
                    }
                return str;
                }
        </script>
    </head>
    <body>
        <script type="text/javascript">
        var a = "A"
        var b = "B"
        document.write(qq('$a but not $b'))
        </script>
        <hr />
        <script type="text/javascript">
            function aTest()
                {
                this.c = "C"
                this.d = "D"
                this.qq = qq;
                document.write(qq('$c but not $d'))
                }
            aTest()
        </script>
    </body>
</html>

Rather than declare local variables using the var keyword, instead make them as objects of the function. Also make the qq function a property of the local function and then you can use it to show the contents of those localized variables.

mordred · 07-24-2002, 11:04 AM

I'm a firm believer that eval() is inherently evil. So I would like to point out an alternative to it for this interesting function:

Code:

function qq(str) {
    while (str.indexOf('$') != -1) {
        str = str.replace(/\$[^\s\W]+/, this[str.match(/\$([^\s\W]+)/, "$1")[1]]);
    }
    return str;
}

When this function is called from the global scope, then "this" will point to window - in which all global variables are contained. If you call qq from a function, then it will try to find properties of that function instead, as outlined above by Roy Sinclair.

Just thinking about it, but have you also considered doing a global replace with backreference to a matched subpattern?