javascript the string.replace method and its use
string.replace method accept a regexpression as the seperator, also, you can pass some anonymous function which will work on each of the matched method;
let's see the example.
/**************************************
*@Summary
* this file demonstrate the use of string.replace method, which can accept some regexpression and an additional function which works on each and every element that is returned by the match
*
*
* @Usage:
*
* compress( "foo=1&foo=2&blah=a&blah=b&foo=3" ) == "foo=1,2,3&blah=a,b"
*
* @TODO:
* some more practical use of the string.replac method call
* assert("a b c".replace(/a/, function() { return ""; } ) == " b c", "returning an empty result removes a match");
***************************************/
function compress(data) {
var q = [], ret = [];
// in the anonymouse function, the first argument is the entire match, and followed by each, subsequent capture following.
data.replace(/([^=&]+)=([^&]*)/g, function(m, key, value) {
q[key] = (q[key] ? q[key] + "," : "") + value;
// why do we need to return a empty string?
// the return value of the replace method call will be injected back to the string as replacement.
// by returning a empty string, we are clearning the matched values.
return "";
});
for (var key in q)
{
ret.push(key + "=" + q[key]);
}
return ret.join("&");
}
and below is the code that test the functions above, which also shows you the tricks on how to make use of the return value from the anonymous function.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<script type="text/javascript" src="strregex.js" ></script>
<script type="text/javascript" src="../unit.js"></script>
<script type="text/javascript">
window.onload = function () {
test("test string replace method call", function () {
assert(compress("foo=1&foo=2&blah=a&blah=b&foo=3") == "foo=1,2,3&blah=a,b", "verity the compression method");
});
test("Test string replace method 2", function () {
assert("a b c".replace(/a/, function () { return ""; }) == " b c", "Returning an empty result removes a match.");
});
};
</script>
<style>
#results li.pass { color: Green }
#results li.fail { color: Red}
</style>
</head>
<body>
<ul id="results" />
</body>
</html>