You're right about the array and I did forget about the null check. This both String have a different pointer. Of course the string.Length == 0 check should be the fastest since Length is a property and there shouldn't be any processing other than retrieving the value of the property. Would it be possible, given current technology, ten years, and an infinite amount of money, to construct a 7,000 foot (2200 meter) aircraft carrier? I suggest you to do a further reading on the differences between literal notation and constructors on javascript to find more details. This output was obtained as the second condition is true for empty value. In JavaScript, the operator is a little bit trickier and more powerful. The IS NULL constraint can be used whenever the column is empty and the symbol ( ) is used How do I read / convert an InputStream into a String in Java? Ready to optimize your JavaScript with Rust? JavaScript check if variable exists (is defined/initialized) Ask Question Asked 11 years, 9 months ago. While do you use "new Object({})", you will have different instances. So if (string == null) is true, the length part does not need to be evaluated, as the expression would always be true. You can check if the users array contains a given value by using the array.find(predicate) method. For node developers, in addition to dist, the zxcvbn npm module includes a lib directory (hidden from git) that includes one compiled .js and .js.map file for every .coffee in src. How do I test for an empty JavaScript object? To remove a marker from the map, call the setMap() method passing null as the argument. Ready to optimize your JavaScript with Rust? Should teachers encourage good students to help weaker ones? The only exception is when checking for undefined and null by way of null. Yes, There is a difference, they're not the same. Ready to optimize your JavaScript with Rust? Object.prototype.toString.call(d) === '[object Date]' A call to getTime() as in Borgar's answer is unnecessary as isNaN() and isFinite() both implicitly convert to number. Throw a message whenever ua ser does not fill the text box value. You cannot call any instance methods on a null variable. The code in the if block wouldn't run if the str variable is set to an empty string, undefined, null, 0, false or NaN. WebStrict equality checks (===) should be used in favor of ==. marker.setMap(null); Note that the above method does not delete Is this an at-all realistic configuration for a DHC-2 Beaver? lol. I use underscore's isNaN function because in JavaScript: I just want to share another alternative, it's not necessarily better than others here, but I think it's worth looking at: The logic behind this is that every number except 0 and NaN are cast to true. The performance is slightly better (not much), and doesn't require object creation (though most compilers might optimize this out). This returns true only for NaN values and Is a safe way of testing. Include an inline