为什么按位异或在JavaScript的if语句中不起作用？

Question

Could somebody explain this behavior?

https://jsfiddle.net/td1qtyxL/9/

function checkSignsWeird(a,b){
    var output = "";
    if(a^b < 0){
        output = "The "+a+" and "+b+" have DIFFERENT signs.";
    }else{
        output = "The "+a+" and "+b+" have the SAME sign.";
    }
    console.log(output);
}

Basically unless a^b is stored in a variable (or wrapped in parentheses), it doesn't work.

checkSignsWeird(-50,40);
checkSignsWeird(60,70);

Both produce the same result.

Amy I doing something wrong or is this a bug? Does bitwise work differently when it's in an if clause or when it's elsewhere? I don't often work with bitwise, just thought this was elegant, following up on an answer from here: Check if two integers have the same sign

Answer 1

The "Less Than" (<) has a higher precedence than the bitwise XOR (^): https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence#Table

You need to group the operation with parentheses.

Answer 2

Bitwise operators have a lower precedence than comparison operators. See Operator precedence .

That being said, don't write clever code.

function haveSameSign(a, b) {
    return (a >= 0 && b >= 0) || (a < 0 && b < 0);
}