simpleCalculator.js

const one = document.getElementById("1");
const two = document.getElementById("2");
const three = document.getElementById("3");
const four = document.getElementById("4");
const five = document.getElementById("5");
const six = document.getElementById("6");
const seven = document.getElementById("7");
const eight = document.getElementById("8");
const nine = document.getElementById("9");
const zero = document.getElementById("0");
const add = document.getElementById("+");
const subtract = document.getElementById("-");
const divide = document.getElementById("/");
const multiply = document.getElementById("*");
const equals = document.getElementById("=")
const clear = document.getElementById("clear");
const dot = document.getElementById('dot')
let display = document.getElementById("display");
let operation = document.getElementById("operation")
let answer = document.getElementById("answer")
let input = "";
let parse = [];
let operators = ['+', '-', '*', '/'];

function addToDisplay(e){
    let selection = e.target.textContent;
    let dotcheck = /\./;
    let endondot = /\.$/;
    if(operation.textContent === '' && operators.includes(selection)){
        operation.textContent = answer.textContent + selection;
        parse.push(answer.textContent);
        parse.push(selection);
        console.log("1")
    }
    else if(operators.includes(parse[parse.length-1]) === true && operators.includes(parse[parse.length-2]) === false && selection === '-'){
        operation.textContent += selection;
        parse.push(selection);
        console.log("2")
    }
    else if((operators.includes(parse[parse.length -1]) && operators.includes(selection)) || (dotcheck.test(parse[parse.length-1]) && selection === '.')){
        console.log("exit")
        return;
    }
    else if(selection === '.' && (operators.includes(parse[parse.length-1]) || operation.textContent === '')){
        console.log(parse)
        operation.textContent += '0' + selection;
        parse.push('0' + selection);
    }
    else if((operators.includes(parse[parse.length-1]) && operators.includes(parse[parse.length-2]) === false)|| operation.textContent === ''){
        operation.textContent += selection;
        parse.push(selection);
        console.log('3')
    }
    else if(operators.includes(selection) === false || parse[parse.length-1] === '-'){
        operation.textContent += selection;
        parse[parse.length-1] += selection;
        console.log('4')
    }
    else if(endondot.test(parse[parse.length-1])){
        operation.textContent += '0' + selection;
        parse[parse.length-1] += '0';
        parse.push(selection);
    }
    else{
        operation.textContent += selection;
        parse.push(selection);
        console.log('5')
    }
    console.log(parse)
    console.log(operators.includes(selection))
}

function clearAll(e){
    answer.textContent = "0";
    operation.textContent = "";
    parse = [];
}

function calculate(e){
    while(parse.length > 1){
        if(operation.textContent === ''){
            return;
        }
        if(parse.includes('*')){
            for(let i = 0; i < parse.length; i++){
                if(parse[i] === '*'){
                    parse.splice((i-1), 3, (parseFloat(parse[i-1])*parseFloat(parse[i+1])))
                }
                console.log(parse)
            }
        }
        if(parse.includes('/')){
            for(let i = 0; i < parse.length; i++){
                if(parse[i] === '/'){
                    parse.splice((i-1), 3, (parseFloat(parse[i-1])/parseFloat(parse[i+1])))
                }
            }
        }
        if(parse.includes('+')){
            for(let i = 0; i < parse.length; i++){
                if(parse[i] === '+'){
                    parse.splice((i-1), 3, (parseFloat(parse[i-1])+parseFloat(parse[i+1])))
                }
                console.log(parse)
            }
        }
        if(parse.includes('-')){
            for(let i = 0; i < parse.length; i++){
                if(parse[i] === '-'){
                    parse.splice((i-1), 3, (parseFloat(parse[i-1])-parseFloat(parse[i+1])))
                    console.log(parse)
                }
            }
        }
}
    answer.textContent = parse[0];
    operation.textContent = '';
    parse = [];
}

one.onclick = addToDisplay;
two.onclick = addToDisplay;
three.onclick = addToDisplay;
four.onclick = addToDisplay;
five.onclick = addToDisplay;
six.onclick = addToDisplay;
seven.onclick = addToDisplay;
eight.onclick = addToDisplay;
nine.onclick = addToDisplay;
zero.onclick = addToDisplay;
add.onclick = addToDisplay;
subtract.onclick = addToDisplay;
multiply.onclick = addToDisplay;
divide.onclick = addToDisplay;
dot.onclick = addToDisplay;
equals.onclick = calculate;
clear.onclick = clearAll;