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javascriptjavagwtsigned

GWT signed zero

In Java I can distinguish between 0D and -0D:

new Double("0").equals(new Double("-0")) // false

But apparently this seems not to work anymore after GWT transpiled my Java to JavaScript. I even get false in GWT dev-mode but true in GWT super-dev-mode.

I've read that in JavaScript

0.0 === -0.0 // true

but

Object.is(0, -0) // false

How can I force GWT to use the Object.is comparision? Or is there any other solution to check if I got a negative or positive zero?

Solution

  • OK, after some more research, I came up with a solution using JSNI:

    native boolean isNegative(double value)
/*-{
    return 1 / value < 0;
}-*/;

    As 1/-0 produces -Infinity in JavaScript, this one works.