how to add numbers in array in javascript code example

Example 1: sum of all numbers in an array javascript

const arrSum = arr => arr.reduce((a,b) => a + b, 0)

Example 2: how to append object in array javascript

var select =[2,5,8];
var filerdata=[];
for (var i = 0; i < select.length; i++) {
  filerdata.push(this.state.data.find((record) => record.id == select[i]));
}
//I have a data which is object,
//find method return me the filter data which are objects
//now with the push method I can make array of objects

Example 3: sum of all elements in array javascript

arrSum = function(arr){  return arr.reduce(function(a,b){    return a + b  }, 0);}