daejinseok · September 10, 2020 13:56
diff --git a/common_javascript_function.js b/common_javascript_function.js
 function makeHashCount( arr ){
    const m = new Map();

    arr.forEach( k => {
        m.set(k, (m.get(k)||0) + 1 );
    })

    return m;
 }

 console.log( makeHashCount([1,2,3,3]) );
 // Map(3) { 1 => 1, 2 => 1, 3 => 2 }
	function makeHashCount( arr ){
	const m = new Map();

	arr.forEach( k => {
	m.set(k, (m.get(k)\|\|0) + 1 );
	})

	return m;
	}

	console.log( makeHashCount([1,2,3,3]) );
	// Map(3) { 1 => 1, 2 => 1, 3 => 2 }