Javascript maps

src/concepts/maps.js

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+/**
+ * MAPS
+ * Maps are similar to javascript objects which holds key value pairs and remembers the original insertion order of keys.
+ */
+
+const map = new Map();
+
+map.set('name', 'jhon doe'); // we use map.set() to insert values into the maps.
+map.set('address', { city: 'hyderabad', place: 'Charminar' }); // can store objects inside maps
+map.has('name'); // -> true (we use map.has() tocheck if a key is existing inside a map)
+map.get('name'); // -> 'jhon doe' (we use map.get() to get a value of a key inside the map)
+map.delete('address'); // we use map.delete() to delete a key and its value inside a map
+console.log(map);

src/problems/detectCapital.js

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+/*
+Given a word, you need to judge whether the usage of capitals in it is right or not.
+
+We define the usage of capitals in a word to be right when one of the following cases holds:
+
+1) All letters in this word are capitals, like "USA".
+2) All letters in this word are not capitals, like "leetcode".
+3) Only the first letter in this word is capital, like "Google".
+Otherwise, we define that this word doesn't use capitals in a right way.
+
+Input: "USA"
+Output: True
+
+Input: "FlaG"
+Output: False
+*/
+
+const detectCapitals = (word) => {
+  if (word.length === 0 || word.length === 1) return true;
+  if (word.toUpperCase() === word) return true; // case 'USA'
+  if (word.toLowerCase() === word) return true; // case 'leetcode'
+  if (word[0] + word.substring(1) === word) return true; // case 'Google'
+  return false;
+};