closed as too broad by user40980, durron597, GlenH7♦, user22815, Dan Pichelman Jul 9 '15 at 19:14
Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.
For example, because of type coercion., 1 == true is true, but 1 === true is false. The == operator often hides type errors.
'' == '0' // false 0 == '' // true 0 == '0' // true false == 'false' // false false == '0' // true false == undefined // false false == null // false null == undefined // true ' \t\r\n ' == 0 // true