added more solution approach with well comments to understand

chapter01/1.1 - Is Unique/isUnique.js

@@ -23,7 +23,7 @@ const everyCharUnique = (str, indexOffset = 'a'.charCodeAt()) => {
     return true;
 };
 
-function everyCharUnique(str) {
+function everyCharUniques(str) {
   let obj = {};
   for (let i = 0; i < str.length; i++) {
     if (obj[str[i]] && obj[str[i]] >= 1) {
@@ -35,8 +35,51 @@ function everyCharUnique(str) {
   return true;
 }
 
+// So we have two methods to one by creating extra space annd without creating extra space
+// with extra spaces
+  let uniqueChars = (str) =>{
+    // creating a empty variable to map
+    let characters = {};
+    // iterate through all characters of the string and start inserting them one by one characters tabole
+      for(var i = 0; i < str.length; i++){
+        // check if string already present in characters variable
+        if(characters[str[i]] != null) {
+          // if present repetation of character than return false
+        characters[str[i]] = 1;
+        return false;
+      }else{
+        // !present duplicate characters than return true
+        characters[str[i]] = 0;
+
+      }
+
+      }
+      return true;
+  }
+// Since we are iterating trough each element of string only once string of length 1 average and worst case time complexity is O(n)
+// without extra spaces
+
+  let uniqueChar = (str) => {
+    // iterate through string
+    for(let i =0; i< str.length; i++){
+      // checking against the subsequent characters & iterating through them
+      for(let j = i+1; j <=str.length-1; j++){
+        if(str[i] == str[j]){
+          return false;
+        }
+      }
+    }
+    return true;
+  }
+
 /* TESTS */
 console.log(everyCharUnique('abcd'), 'true');
 console.log(everyCharUnique('abccd'), 'false');
 console.log(everyCharUnique('bhjjb'), 'false');
-console.log(everyCharUnique('mdjq'), 'true');
+console.log(everyCharUniques('mdjq'), 'true');
+console.log(uniqueChars('hello'), 'false');
+console.log(uniqueChars('anish'), 'true');
+console.log(uniqueChar('hello'), 'false');
+console.log(uniqueChar('anish'), 'true');
+
+