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const map1 = new Map();
map1.set('a', 1);
map1.set('b', 2);
map1.set('c', 3);
console.log(map1.get('a'));
// expected output: 1
map1.set('a', 97);
console.log(map1.get('a'));
// expected output: 97
console.log(map1.size);
// expected output: 3
map1.delete('b');
console.log(map1.size);
// expected output: 2
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Create Empty Map
let myMap = new Map<string, number>();
myMap.set('a', 1);
myMap.set('b', 2);
myMap.set('c', 3);
console.log(myMap.get('a'));
// expected output: 1
myMap.set('a', 97);
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Creating map with initial key-value pairs
let myMap = new Map<string, string>([
["key1", "value1"],
["key2", "value2"]
]);
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Iterating over keys and values in a Map
let nameAgeMapping = new Map<string, number>();
nameAgeMapping.set("Lokesh", 37);
nameAgeMapping.set("Raj", 35);
nameAgeMapping.set("John", 40);
//1. Iterate over map keys
for (let key of nameAgeMapping.keys()) {
console.log(key); //Lokesh Raj John
}
//2. Iterate over map values
for (let value of nameAgeMapping.values()) {
console.log(value); //37 35 40
}
//3. Iterate over map entries
for (let entry of nameAgeMapping.entries()) {
console.log(entry[0], entry[1]); //"Lokesh" 37 "Raj" 35 "John" 40
}
//4. Using object destructuring
for (let [key, value] of nameAgeMapping) {
console.log(key, value); //"Lokesh" 37 "Raj" 35 "John" 40
}
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Map Operations
let nameAgeMapping = new Map<string, number>();
//1. Add entries
nameAgeMapping.set("Lokesh", 37);
nameAgeMapping.set("Raj", 35);
nameAgeMapping.set("John", 40);
//2. Get entries
let age = nameAgeMapping.get("John"); // age = 40
//3. Check entry by Key
nameAgeMapping.has("Lokesh"); // true
nameAgeMapping.has("Brian"); // false
//4. Size of the Map
let count = nameAgeMapping.size; // count = 3
//5. Delete an entry
let isDeleted = nameAgeMapping.delete("Lokesh"); // isDeleted = true
//6. Clear whole Map
nameAgeMapping.clear(); //Clear all entries