What does the JSLint error 'body of a for in should be wrapped in an if statement' mean?

Question

I used JSLint on a JavaScript file of mine. It threw the error:

for( ind in evtListeners ) {

Problem at line 41 character 9:

Answer 1

This means that you should filter the properties of evtListeners with the hasOwnProperty method.

Answer 2

Bad: (jsHint will throw a error)

for (var name in item) {
    console.log(item[name]);
}

Good:

for (var name in item) {
  if (item.hasOwnProperty(name)) {
    console.log(item[name]);
  }
}