Question

How do I convert a negative float (like -4.00) to a positive one (like 4.00)?

Answer 1

The best way to flip the number is simply to multiply it by -1:

console.log( -4.00 * -1 ); // 4

If you’re not sure whether the number is positive or negative, and don’t want to do any conditional checks, you could instead retrieve the absolute value with Math.abs():

console.log( Math.abs( 7.25 ) );     // 7.25
console.log( Math.abs( -7.25 ) );    // 7.25
console.log( Math.abs( null )) ;     // 0
console.log( Math.abs( "Hello" ) );  // NaN
console.log( Math.abs( 7.25-10 ) );  // 2.75

Note, this will turn -50.00 into 50 (the decimal places are dropped). If you wish to preserve the precision, you can immediately call toFixed on the result:

console.log( Math.abs( -50.00 ).toFixed( 2 ) ); // '50.00'

Keep in mind that toFixed returns a String, and not a Number. In order to convert it back to a number safely, you can use parseFloat, which will strip-off the precision in some cases, turning '50.00' into 50.