CODEWITHSUNDEEP
javascriptjquerycalculator
Echo0831
Echo0831

Reputation: 307

How to implement a plus/minus button in a calculator work?

I want to create a button on the calculator that could convert a positive number into a negative one and also could change a negative number into a positive number.

Here is the code in js:

function reverse_num(){
    var num = $( "#p").text();
    if(num > 0){
        $("p").prepend("-");
    }
    else if(num = 0)
    {
        $("p");
    }
}

When I want to convert a positive into a negative, it works fine. But I have no idea what to do when I want to remove that negative sign.

Could someone show me how to do?

Upvotes: 3

Views: 5354

Answers (2)

Uttam Kumar Roy
Uttam Kumar Roy

Reputation: 2058

You could use this by two way

Way 1: You can remove "-" by using replace('-', '');

Way 2 : You can also use multiplication by (-1)

function reverse_num(){
    var num = $( "#p").text();
	if(num > 0){    
       $("p").prepend("-");
	}
	else if(num < 0){
        var num = $( "#p").text().replace('-', '');
		$("#p").text(num);
	}
	else if(num == 0){
	   $("#p");
	} 
}

reverse_num();

function reverse_num_version_2(){
    var num = $( "#number").text();
	if(num > 0){    
       $("#number").prepend("-");
	}
	else if(num < 0){
        num = num * (-1);
		$("#number").text(num);
	}
	else if(num == 0){
	   $("#number");
	} 
}
reverse_num_version_2();
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<p id="p">-100</p>

<div id="number">-100</div>

Upvotes: 1

Vinny M
Vinny M

Reputation: 770

You should use basic math and multiply by -1 when the minus sign is clicked.

e.g.:

//Get the number
var number = parseFloat( $( "#p").text() );

//Reverse it
function reverse_num(num) {
    return (-num); // == (-1 * num)
}

//Replace the content of #p
$("#p").text( reverse_num(number) );

As a "oneliner"

$("#p").text(-(parseFloat($("#p").text())));

Upvotes: 1

Related Questions