js groupBy

function groupBy( array , id ) {
    let groups = {};
    array.forEach( function( o ) {
        let group = JSON.stringify( o[id] );
        groups[group] = groups[group] || [];
        groups[group].push( o );
    });
    return Object.values(groups);
}
let name = "name"
let list = [
    {"name": "John","Average":15,"High":10,"DtmStamp":1358226000000},
    {"name": "Jane","Average":16,"High":92,"DtmStamp":1358226000000},
    {"name": "Jane","Average":17,"High":45,"DtmStamp":1358226000000},
    {"name": "John","Average":18,"High":87,"DtmStamp":1358226000000},
    {"name": "Jane","Average":15,"High":10,"DtmStamp":1358226060000},
    {"name": "John","Average":16,"High":87,"DtmStamp":1358226060000},
    {"name": "John","Average":17,"High":45,"DtmStamp":1358226060000},
    {"name": "Jane","Average":18,"High":92,"DtmStamp":1358226060000}
];
let sorted = groupBy(list, name);
console.log(sorted);