check if key in map js code example

Example 1: javascript does key exist

var person={"name":"Billy","age":20}
person.hasOwnProperty("name"); // true
person.hasOwnProperty("sex"); // false

Example 2: check if a key is in a map

if ( m.find("f") == m.end() ) {
  // not found
} else {
  // found
}

Example 3: js key in dict

"key" in obj // true, regardless of the actual value

Example 4: js check if map contains key

const map1 = new Map();
map1.set('bar', 'foo');

console.log(map1.has('bar'));
// expected output: true

console.log(map1.has('baz'));
// expected output: false