Data Structures: Create a Hash Table

Data Structures/hashTable.js

@@ -0,0 +1,50 @@
+// https://www.freecodecamp.org/learn/coding-interview-prep/data-structures/create-a-hash-table
+
+var called = 0;
+var hash = (string) => {
+  called++;
+  var hashed = 0;
+  for (var i = 0; i < string.length; i++) {
+    hashed += string.charCodeAt(i);
+  }
+  return hashed;
+};
+var HashTable = function () {
+  this.collection = {};
+  // Only change code below this line
+  this.add = (k, v) => {
+    const keyHash = hash(k);
+    if (this.collection[keyHash] === undefined) {
+      this.collection[keyHash] = [[k, v]];
+    } else {
+      this.collection[keyHash].push([k, v]);
+    }
+  };
+
+  this.remove = (k) => {
+    const keyHash = hash(k);
+    if (this.collection[keyHash] === undefined) {
+      return;
+    }
+    this.collection[keyHash] = this.collection[keyHash].filter(
+      ([key, value]) => key !== k
+    );
+    if (this.collection[keyHash].length === 0) {
+      delete this.collection[keyHash];
+    }
+  };
+
+  this.lookup = (k) => {
+    const keyHash = hash(k);
+    if (this.collection[keyHash] === undefined) {
+      return null;
+    }
+    for (let [key, value] of this.collection[keyHash]) {
+      if (key === k) {
+        return value;
+      }
+    }
+    return null;
+  };
+  // Only change code above this line
+};