equivalence

I've been reading Douglas Crockford's JavaScript: The Good Parts , and I came across this weird example that doesn't make sense to me: '' == '0' // false 0 == '' // true 0 == '0' // true false == undefined // false false == null // false null == undefined // true The author also goes on to mention "to never use == and != . Instead, always use === and !== ". However, he doesn't explain why the above behavior is exhibited? So my question is, why are the above results as they are? Isn't transitivity considered in JavaScript? alex '' == '0' // false The left hand side is an empty string, and the

I've been trying to understand the difference between JavaScript's comparison operators: identity and equality. From what I've read, if you check the equality of two objects using ==, JavaScript will try to figure out if they are the same type and, if not, try to get them to that same type. However, === doesn't behave in the same manner. So as an example: var n = "1"; console.log(n==1); // outputs true console.log(n===1); // outputs false So what is the difference between these "identity" operators and the regular equality operators? What is the benefit of having both? Are there differences in