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script.js
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script.js
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const op_div = document.querySelector('#op');
const result_div = document.querySelector('#result');
const all_numbers = document.querySelectorAll('.number');
const all_ops = document.querySelectorAll('.operator');
const clear_button = document.querySelector('#clear');
const point_button = document.querySelector('#point');
const DECIMAL_PLACES = 6;
function _throw(m) { throw m; } //for throwing exception inside ternary op
Number.prototype.countDecimals = function () {
if(Math.floor(this.valueOf()) === this.valueOf()) return 0;
return this.toString().split(".")[1].length || 0;
}
const add = (x,y) => x+y ;
const substract = (x,y) => x-y ;
const multiply = (x,y) => x*y;
const divide = (x,y) => y != 0 ? x/y : _throw('can not divide by 0') ;
const symbol2func = {
'+':add,
'-':substract,
'*':multiply,
'/':divide
}
let old_number = null;
let curr_number = null;
let answer = null;
let chosen_symbol = null;
let clean_after_op = false;
let floating_point = false;
let floating_zeros = 0;
function updateOperationDiv(putEqual,addZeros2Curr){
let text = chosen_symbol !== null ? old_number + chosen_symbol : '';
text += curr_number !== null ? curr_number + addZeros2Curr : '' ;
text += putEqual ? '=' : '';
op_div.textContent = text;
result_div.textContent = answer;
}
function updateCurrNumber(val){
let addZeros2Curr = '';
if (floating_point){
if (curr_number.countDecimals() == DECIMAL_PLACES){
return;
}
if(val == 0){
floating_zeros += 1
addZeros2Curr = curr_number % 1 === 0 ?'.' + ('0'.repeat(floating_zeros )) : ('0'.repeat(floating_zeros )) ;
}
else{
curr_number = curr_number !== null ? parseFloat(( parseInt(val) / Math.pow(10,(curr_number.countDecimals()+floating_zeros+ 1))+ curr_number).toFixed(DECIMAL_PLACES)) : parseInt(val) / 10;
floating_zeros = 0;
}
}
else{
curr_number = curr_number !== null ? parseInt(val) + curr_number * 10 : parseInt(val);
}
if (answer){
answer = null;
}
updateOperationDiv(false,addZeros2Curr);
}
function updateOperation(symbol){
if (symbol === '='){
//there is an ongoing operation then calculate the result
if(chosen_symbol && (curr_number !== null)){
try {
answer = symbol2func[chosen_symbol](old_number,curr_number);
}
catch(err){
alert(err);
return;
}
if (answer % 1 !== 0){
answer = parseFloat(answer.toFixed(DECIMAL_PLACES));
}
updateOperationDiv(true,'');
old_number = null;
curr_number = null;
floating_point = false;
floating_zeros = 1;
point_button.disabled =false
chosen_symbol = null;
}
}
else {
if (chosen_symbol && (curr_number !== null)){
try {
answer = symbol2func[chosen_symbol](old_number,curr_number);
}
catch(err){
alert(err);
return;
}
if (answer % 1 !== 0){
answer = parseFloat(answer.toFixed(DECIMAL_PLACES));
}
updateOperationDiv(true,'');
curr_number = null;
floating_point = false;
floating_zeros = 1;
point_button.disabled =false
chosen_symbol = symbol;
old_number = answer;
}
else if (answer !== null){
chosen_symbol = symbol;
old_number = answer;
curr_number = null;
floating_point = false;
floating_zeros = 1;
point_button.disabled =false;
updateOperationDiv(false,'');
}
else if(curr_number !== null){
chosen_symbol = symbol;
old_number = curr_number;
curr_number = null;
floating_point = false;
floating_zeros = 1;
point_button.disabled =false;
updateOperationDiv(false,'');
}
}
}
all_numbers.forEach(number_button => {
number_button.addEventListener('click',() =>{updateCurrNumber(number_button.textContent)});
});
all_ops.forEach(operator_button => {
operator_button.addEventListener('click',() =>{updateOperation(operator_button.textContent)});
});
clear_button.addEventListener('click', () => {
location.reload(); //reload page
});
point_button.addEventListener('click', () => {
floating_point = true;
point_button.disabled =true;
});