Get the Sum result in NEGATIVE of positive integers

Question

I am adding two numbers with jQuery and I need to get the result in NEGATIVE even if the integers are positive, i.e

var sum = (5 + 10);
console.log(sum)  // Expected result is -15
                  // Current result is 15

Tried concatenating like

sum = '-' + (a + b) // But since the string is being added to number it's not working the expected way. 

Need a little help on the same. Thanks

Answer 1

Don't use - as string, when you use '-' with + operator, the number is casted to string and the result will be '-15' as string. In this case + operator is used as string concatenation operator.

Using '-' in the expression, you're not using this as operator, it is string. Use - without quotes to use it as arithmetic minus operator.

var sum = -(a + b); // -15

This will give you the negated result. If the result of the expression is itself negative e.g. (-10 + 5) above expression will give you result 5.

In case if you always want the negative result

var sum = -(a + b) >= 0 ? (a + b) : -(a + b);

Answer 2

The negative sign - is a valid operator in Javascript, so there is no need to use it as a string.

You can do:

var sum = -(5 + 10);

Which is how you would declare a negative number:

var negativeNumber = -123;

Grouping has the highest precedence of any operators in Javascript, so your addition would be done first, and then the subtraction would be applied.

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Or if you want it to look nicer mathematically you could multiply by a negative one:

var sum = (5 + 10) * -1;

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As @Hanky 웃 Panky points out in his answer, you might want to check to see if your sum is already negative, before applying a negation.

Answer 3

You can achieve this with simple multiplication of result with -1.

var num_1 = 10;
var num_2 = 20;
var Negative = -1

var result = (parseInt(num_1) + parseInt(num_2)) * Negative;

The output would be -30