jshint no error for forin (hasOwnProperty)

Question

Why jshint is not reporting forin (hasOwnProperty) error for the following code? jslint do report error on it but jshint doesn't.

/*jshint forin: true */

(function () {
    "use strict";

    var obj = {a: 1, b: 2}, i = null;

    for (i in obj) {
        if (i === 0) {
            console.log('blah...');
        }
    }
}());

Answer 1

Here's the relevant snippet of code from JSHint (modified slightly for formatting):

if (
    state.option.forin && 
    s && 
    (s.length > 1 || typeof s[0] !== "object" || s[0].value !== "if")
) {
    warning("W089", this);
}

The important part is s[0].value !== "if". JSHint won't raise an error if the first statement of the for...in body is an if statement, regardless of the condition of that statement.