Make a JavaScript Calculator

[StoneCold]

Hey guys, I need to make a calculator
I have buttons for 0-9, digits = button, . button and have +, -, *, /, modules and square root operators and CE, M+, M- and backspace.
I have made the interface. Now all I want is make the javascript code.
It will be simple, I need a function for each and every operator. and also a switch case. can you guys plz help me??? thank you all..........
1 Minute Ago #1

[Jwalker]

Use "eval()" function.
Each button writes his symbol in a textbox. Then evaluate the text entered using the eval function.
Try to start it

[sainathsagar]

eval() function is quite easy to use !!

[Dormilich]

eval() function is quite easy to use !!

eval() function is quite easy to abuse !!

if you’re not extremely careful, any attacker has your site in his hands.


PS. be aware of floating point arithmetics’ traps

// e.g.
var sum = 0.1 + 0.2;
alert(sum == 0.3);

[acoder]

I need a function for each and every operator. and also a switch case.

What have you managed have so far? Give your attempt for, e.g., the + and = buttons. This will make it easier for someone to help you.

[Anas Mosaad]

eval() function is quite easy to abuse !!

if you’re not extremely careful, any attacker has your site in his hands.

Dormilich, just to remind you. JavaScript is client side. I don't believe that an attacker can do something harmful to his site with eval(). However, it's a good programming practice to handle all such issues.

[StoneCold]

@all Guys I don't need to use eval function. Teacher said don't use it.
here is my = function

function equals() {
CurentDisplayValue = eval(document.frmOne.txtDisplay.value)
PreviousDisplayValue = eval(total)
 
if(TheOperator =="+") {
    answer = PreviousDisplayValue + CurentDisplayValue
}
else if(TheOperator == "*") {
    answer = PreviousDisplayValue * CurentDisplayValue
}
else if(TheOperator == "-") {
    tanswer = PreviousDisplayValue - CurentDisplayValue
}
else if(TheOperator == "/") {
    answer = PreviousDisplayValue / CurentDisplayValue
}
document.frmOne.txtDisplay.value = answer
}

how to create the equall buttun without eval?