Add 1.6 String Compression solution

Author: rroque98

JavaScript/chapter01/1.6 - String Compression/rroque98_sol.js

@@ -0,0 +1,33 @@
+/* Implement a method to perform basic string 
+compression using the counts of repeated characters
+Ex: 'aabcccccaaa' would become a2b1c5a3
+*/
+
+const stringCompression = (str) => {
+  if (!str.length) {
+    return '';
+  }
+  var compStr = '';
+  var count = 1;
+  var currentChar = str[0];
+  for (let i = 1; i < str.length; i++) {
+    let char = str[i];
+    if (char === currentChar) {
+      count++;
+      if (i === str.length - 1) {
+        compStr += `${currentChar}${count}`;
+      }
+    } else {
+      compStr += `${currentChar}${count}`;
+      currentChar = char;
+      count = 1;
+    }
+  }
+  return compStr;
+}
+
+// TESTS
+console.log(stringCompression('aabcccccaaa') === 'a2b1c5a3');
+console.log(stringCompression('cccccccc') === 'c8');
+console.log(stringCompression('') === '');
+console.log(stringCompression('AabccCccaaa') === 'A1a1b1c2C1c2a3');