Jun 3, 2012 · This is the strict not equal operator and only returns a value of true if both the operands are not equal and/or not of the same type. The following examples return a Boolean true: a !== b a !== "2" 4 !== '4'

NaN is not equal to anything, including NaN. Positive and negative zeros are equal to one another. Two Boolean operands are strictly equal if both are true or both are false. Two objects are strictly equal if they refer to the same Object. Null and Undefined types are == (but not ===). [I.e. (Null==Undefined) is true but (Null===Undefined) is ...

Dec 11, 2008 · In the answers here, I didn't read anything about what equal means. Some will say that === means equal and of the same type, but that's not really true. It actually means that both operands reference the same object, or in case of value types, have the same value. So, let's take the following code:

I want to write an if/else statement that tests if the value of a text input does NOT equal either one of two different values. Like this (excuse my pseudo-English code): var test = $("#test").val...

Aug 27, 2010 · Not only is it safe, but in many cases it simplifies your code in a way that improves readability. I still recommend Crockford's talk for developers who don't want to invest the time to really understand Javascript—it's good advice for a …

In the other hand, a var equal to "" is a defined var pointing to a variable which contains an empty string. That's essentially different. [EDIT] As @jfriend00 correctly points out, null is a specific value in javascript. The difference would be then that null is a different value than "", which is an empty string and therefor not null.

Jul 15, 2013 · If it is not found, just for safety purposes it returns -1. This is because 0 is an index in the object. For example: "hello world" h = 0 e = 1 l = 2 ... so if it is not found it will be -1, and if it is found it will be >= (greater than or equal to) 0. so essentially != …

Oracle on the other hand would not evaluate "\0" as being null, preferring to treat it as a string of length 1 (where that one character is the null character). This could cause confusion if not dealt with properly, because many web-developers do work with a back-end database, which might pass through different types of "null" values.

The Double Not Version has faster performance than both the Strict Not Version and the Non-Strict Not Version. However, the !! operator will typecast "falsey" values like 0 , '' , undefined and NaN into false , which may lead to unexpected results, and it has worse readability because null isn't explicitly stated.

The first a of each is not actually a simple a. If you position the cursor right after it and hit Backspace, you delete "something", and then it returns true . I copied your a string, this is what I get when running this code: