how to pick the unique key from array of object javascript code example

Example 1: javascript get unique values from key

const unique = [...new Set(array.map(item => item.age))];

Example 2: javascript find unique values in array of objects

var flags = [], output = [], l = array.length, i;
for( i=0; i<l; i++) {
    if( flags[array[i].age]) continue;
    flags[array[i].age] = true;
    output.push(array[i].age);
}