Add solution to 1.2 Check Perm

Author: rroque98

JavaScript/chapter01/1.2 - Check Perm/rroque98_sol.js

@@ -0,0 +1,37 @@
+/*Given two strings, write a method to decide
+if one is apermutation of the other permutation:*/
+
+const isPermutation = (str1, str2) =>{
+  if (str1.length !== str2.length) {
+    return false;
+  }
+  const obj1 = determineCharCount(str1);
+  const obj2 = determineCharCount(str2);
+  for (let char of str1) {
+    if (obj1[char] !== obj2[char]) {
+      return false;
+    }
+  }
+  return true;
+  //******** helper function ******
+  function determineCharCount(string) {
+    const obj = {};
+    for (let char of string) {
+      if (obj[char] !== undefined) {
+        obj[char]++;
+      } else {
+        obj[char] = 1;
+      }
+    }
+    return obj;
+  }
+}
+
+// Tests:
+  console.log(isPermutation('abc', 'abb') === false);
+  console.log(isPermutation('abb', 'abc') === false);
+  console.log(isPermutation('aaa', 'abc') === false);
+  console.log(isPermutation('abc', 'abcd') === false);
+  console.log(isPermutation('abc', 'bac') === true);
+  console.log(isPermutation('', '') === true);
+  console.log(isPermutation('12', '21') === true);