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 per ECMA 5.1 Standard Specifications, the following table is used to determine the truthyness of an expression

+-----------------------------------------------------------------------+
| Argument Type | Result                                                |
|:--------------|------------------------------------------------------:|
| Undefined     | false                                                 |
|---------------|-------------------------------------------------------|
| Null          | false                                                 |
|---------------|-------------------------------------------------------|
| Boolean       | The result equals the input argument (no conversion). |
|---------------|-------------------------------------------------------|
| Number        | The result is false if the argument is +0, −0, or NaN;|
|               | otherwise the result is true.                         |
|---------------|-------------------------------------------------------|
| String        | The result is false if the argument is the empty      |
|               | String (its length is zero); otherwise the result is  |
|               | true.                                                 |
|---------------|-------------------------------------------------------|
| Object        | true                                                  |
+-----------------------------------------------------------------------+