part1.js

var input = document.getElementsByTagName("pre")[0].innerText.split("\n").filter(e => e !== "");
var previous = 100000000;
var increased = 0;

input.forEach(line => {
    var val = parseInt(line);

    if (val > previous) {
        increased++;
    }
    previous = val;
});

console.log(increased);

part2.js

var input = document.getElementsByTagName("pre")[0].innerText.split("\n").filter(e => e !== "").map(Number);

var newInput = []
for (var i = 2; i < input.length; i++){ 
    newInput.push(input[i]+input[i-1]+input[i-2]);
}

var increased = 0;
var previous = 1000000000000000;

newInput.forEach(val => {
    if (val > previous) {
        increased++;
    }
    previous = val;
});

console.log(increased)