how to convert -1 to 1 with javascript?

how to convert -1 to 1 with javascript ?

var count = -1; //or any other number -2 -3 -4 -5 ...

or

var count = 1; //or any other number 2 3 4 5 ...

result should be

var count = 1; //or any other number 2 3 4 5开发者_如何学JAVA ...

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 count = Math.abs(count)
 // will give you the positive value of any negative number

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The abs function turns all numbers positive: i.e Math.abs( -1 ) = 1

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Alternative approach (might be faster then Math.abs, untested):

count = -5;
alert((count ^ (count >> 31)) - (count >> 31));

Note that bitwise operations in javascript are always in 32-bit.

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If the number of interest is input... In addition to Math.abs(input)....

var count = (input < 0 ? -input : input);

jsFiddle example

(edit: as Some pointed out -input is faster than -1 * input)

The above makes use of the Javascript conditional operator. This is the only ternary (taking three operands) Javascript operator.

The syntax is:

condition ? expr1 : expr2

If the condition is true, expr1 is evaluated, if it's fales expr2 is evaluated.