javascript if else 速记和字符串

Question

 var x = 'x' x-'m'||console.log('True 1') // logs True, should be false var x = '2' x-2||console.log('True 2') // logs True var x = '3' x-2||console.log('True 3') // logs False

Why does this if else shorthand always return true when using a string? How can it be fixed?

I learnt this from here

Answer 1

If the expression before the ||returns a falsy expression, then the console.log() is executed. This happens for the first expression 'x' - 'm' which produces NaN (which is falsy):

 console.log('x' - 'm')

and for the second expression '2' - 2 which returns 0 (which is falsy):

 console.log('2' - 2)

Your console.log() does not get executed for the third expression '3' - 2 because that returns 1 (which is truthy):

 console.log('3' - 2)