Initial data commit

Task/Reverse-a-string/JavaScript/reverse-a-string-1.js

@@ -0,0 +1,9 @@
+example = 'Tux 🐧 penguin';
+
+// array expansion operator
+[...example].reverse().join('') // 'niugnep 🐧 xuT'
+// split regexp separator with Unicode mode
+example.split(/(?:)/u).reverse().join('') // 'niugnep 🐧 xuT'
+
+// do not use
+example.split('').reverse().join(''); // 'niugnep \udc27\ud83d xuT'

Task/Reverse-a-string/JavaScript/reverse-a-string-2.js

@@ -0,0 +1,11 @@
+a = "\u{1F466}\u{1F3FB}\u{1f44b}"; // '👦🏻👋'
+
+// wrong behavior - ASCII sequences
+a.split('').reverse().join(''); // '\udc4b🁦\ud83d'
+
+// wrong behavior - Unicode code points
+[...a].reverse().join(''); // '👋🏻👦'
+a.split(/(?:)/u).reverse().join(''); // '👋🏻👦'
+
+// correct behavior - Unicode graphemes
+[...new Intl.Segmenter().segment(a)].map(x => x.segment).reverse().join('') // 👋👦🏻

Task/Reverse-a-string/JavaScript/reverse-a-string-3.js

@@ -0,0 +1,17 @@
+//using chained methods
+function reverseStr(s) {
+  return s.split('').reverse().join('');
+}
+
+//fast method using for loop
+function reverseStr(s) {
+  for (var i = s.length - 1, o = ''; i >= 0; o += s[i--]) { }
+  return o;
+}
+
+//fast method using while loop (faster with long strings in some browsers when compared with for loop)
+function reverseStr(s) {
+  var i = s.length, o = '';
+  while (i--) o += s[i];
+  return o;
+}

Task/Reverse-a-string/JavaScript/reverse-a-string-4.js

@@ -0,0 +1,18 @@
+(() => {
+
+    // .reduceRight() can be useful when reversals
+    // are composed with some other process
+
+    let reverse1 = s => Array.from(s)
+        .reduceRight((a, x) => a + (x !== ' ' ? x : ' <- '), ''),
+
+        // but ( join . reverse . split ) is faster for
+        // simple string reversals in isolation
+
+        reverse2 = s => s.split('').reverse().join('');
+
+
+    return [reverse1, reverse2]
+        .map(f => f("Some string to be reversed"));
+
+})();

Task/Reverse-a-string/JavaScript/reverse-a-string-5.js

@@ -0,0 +1 @@
+["desrever <- eb <- ot <- gnirts <- emoS", "desrever eb ot gnirts emoS"]