Example 1: javascript reduce array of objects
var objs = [
{name: "Peter", age: 35},
{name: "John", age: 27},
{name: "Jake", age: 28}
];
objs.reduce(function(accumulator, currentValue) {
return accumulator + currentValue.age;
}, 0); // 35 + 27 + 28 = 90
Example 2: javascript reduce
var array = [36, 25, 6, 15];
array.reduce(function(accumulator, currentValue) {
return accumulator + currentValue;
}, 0); // 36 + 25 + 6 + 15 = 82
Example 3: reduce javascript
const sum = array.reduce((accumulator, element) => {
return accumulator + element;
}, 0);
// An example that will loop through an array adding
// each element to an accumulator and returning it
// The 0 at the end initializes accumulator to start at 0
// If array is [2, 4, 6], the returned value in sum
// will be 12 (0 + 2 + 4 + 6)
const product = array.reduce((accumulator, element) => {
return accumulator * element;
}, 1);
// Multiply all elements in array and return the total
// Initialize accumulator to start at 1
// If array is [2, 4, 6], the returned value in product
// will be 48 (1 * 2 * 4 * 6)
Example 4: javascript sum array values
function getArraySum(a){
var total=0;
for(var i in a) {
total += a[i];
}
return total;
}
var payChecks = [123,155,134, 205, 105];
var weeklyPay= getArraySum(payChecks); //sums up to 722
Example 5: reduce
// Array.prototype.reduce()
const array1 = [1, 2, 3, 4];
const reducer = (accumulator, currentValue) => accumulator + currentValue;
// 1 + 2 + 3 + 4
console.log(array1.reduce(reducer));
// expected output: 10
// 5 + 1 + 2 + 3 + 4
console.log(array1.reduce(reducer, 5));
// expected output: 15
Example 6: reduce
var sum = _.reduce([1, 2, 3], function(memo, num){ return memo + num; }, 0);
=> 6