js reduce sum items of array
var array = [
{ Id: "001", qty: 1 },
{ Id: "002", qty: 2 },
{ Id: "001", qty: 2 },
{ Id: "003", qty: 4 }
];
var result = [];
array.reduce(function(res, value) {
if (!res[value.Id]) {
res[value.Id] = { Id: value.Id, qty: 0 };
result.push(res[value.Id])
}
res[value.Id].qty += value.qty;
return res;
}, {});
console.log(result)
<button onclick="myFunction()">Try it</button>
<p>Sum of numbers in array: <span id="demo"></span></p>
<script>
var numbers = [15.5, 2.3, 1.1, 4.7];
function getSum(total, num) {
return total + Math.round(num);
}
function myFunction(item) {
document.getElementById("demo").innerHTML = numbers.reduce(getSum, 0);
}
</script>