if(negetive number) is true? Is something wrong with js?

Question

Is something wrong with js?

if(\"hello\".indexOf(\"world\")) { // I forgot to add > -1 here
    console.log(\"hello world\");
}

Basically

Answer 1

As it was mentioned only 0 (considering numbers) is equivalent to zero. But yes there is list of things which are equal to false in javascript and those are:

1. false
2. null
3. undefined
4. the empty string ""
5. the number 0
6. the number NaN

everything else when comapred to false returns false. e.g. -1 == false -> false