September 2017 Update

Task/Strip-whitespace-from-a-string-Top-and-tail/JavaScript/strip-whitespace-from-a-string-top-and-tail-1.js

@@ -0,0 +1,11 @@
+{
+    let s = " \t String with spaces  \t  ";
+    // a future version of ECMAScript will have trimStart().  Some current
+    // implementations have trimLeft().
+    console.log("original: '" + s + "'");
+    console.log("trimmed left: '" + s.replace(/^\s+/,'') + "'");
+    // a future version of ECMAScript will have trimEnd().  Some current
+    // implementations have trimRight().
+    console.log("trimmed right: '" + s.replace(/\s+$/,'') + "'");
+    console.log("trimmed both: '" + s.trim() + "'");
+ }

Task/Strip-whitespace-from-a-string-Top-and-tail/JavaScript/strip-whitespace-from-a-string-top-and-tail-2.js

@@ -0,0 +1,48 @@
+(() => {
+    'use strict';
+
+    // stripStart :: Text -> Text
+    let stripStart = s => dropWhile(isSpace, s);
+
+    // stripEnd :: Text -> Text
+    let stripEnd = s => dropWhileEnd(isSpace, s);
+
+    // strip :: Text -> Text
+    let strip = s => dropAround(isSpace, s);
+    // OR: let strip = s => s.trim();
+
+
+
+    // GENERIC FUNCTIONS
+
+    // dropAround :: (Char -> Bool) -> Text -> Text
+    let dropAround = (p, s) => dropWhile(p, dropWhileEnd(p, s));
+
+    // dropWhile :: (a -> Bool) -> [a] -> [a]
+    let dropWhile = (p, xs) => {
+        for (var i = 0, lng = xs.length;
+            (i < lng) && p(xs[i]); i++) {}
+        return xs.slice(i);
+    }
+
+    // dropWhileEnd :: (Char -> Bool) -> Text -> Text
+    let dropWhileEnd = (p, s) => {
+        for (var i = s.length; i-- && p(s[i]);) {}
+        return s.slice(0, i + 1);
+    }
+
+    // isSpace :: Char -> Bool
+    let isSpace = c => /\s/.test(c);
+
+    // show :: a -> String
+    let show = x => JSON.stringify(x, null, 2);
+
+
+    // TEST
+
+    let strText = "  \t\t \n \r    Much Ado About Nothing \t \n \r  ";
+
+    return show([stripStart, stripEnd, strip]
+        .map(f => '-->' + f(strText) + '<--'));
+
+})();