JSFiddle - React, Tailwind, and code Playground

JavaScript

var arr = [0, 2, 0, 0, 3, 5]; // a soma deve ser 10
var valor = 2;

function sumFor(arr, nr) {
    var soma = 0;
    for (var x = 0, l = arr.length; x < l; x++) {
        if (arr[x] >= nr) soma += arr[x];
    }
    return soma;
}

function sumReduce(arr, nr) {
    return arr.reduce(
        (sum, val) => sum + (val >= nr ? val : 0)
    );
}

console.log(sumFor(arr, valor));
console.log(sumReduce(arr, valor));