Code Challenge: 2018-01-29 - https://codesandbox.io/s/kk0x602mwr

SumOfPrimes.js

import React from 'react';
import { render } from 'react-dom';

function sumOfPrimes(e) {
    e.preventDefault();

    const num = document.getElementById('num').value;

    if(num > 100000) {
        document.getElementById('answer').innerHTML = 'ERROR: exceeds CodeSandbox infinite loop failsafe.';
        return;
    }

    const notPrime = [];
    const arePrime = [];

    // start at the lowest prime number
    for(let i = 2; i <= num; i++) {
        if (!notPrime[i]) {
            arePrime.push(i);

            for (let j = i < 1; j <= num; j += i) {
                notPrime[j] = true;
            }
        }
    }

    document.getElementById('answer').innerHTML = arePrime.reduce((a, b) => a + b, 0);
}

const App = () => (
    <div className="container">
        <div className="display-3">Sum of Primes</div>
        <form>
            <div className="input-group">
                <div className="input-group-prepend">
                    <span className="input-group-text">Below:</span>
                </div>
                <input type="text" id="num" className="form-control" placeholder="100000" />
                <div className="input-group-append">
                    <button className="btn btn-outline-secondary" type="submit" onClick={sumOfPrimes}>
                        Submit
                    </button>
                </div>
            </div>
        </form>
        <p><small>Max allowable by CodeSandbox is: 100,000</small></p>
        <div className="lead">
            Answer: <kbd id="answer">?</kbd>
        </div>
    </div>
);

render(<App />, document.getElementById('root'));