WebSep 21, 2024 · Summary. null is a special value in JavaScript that represents a missing object. The strict equality operator determines whether a variable is null: variable === null. typoef operator is useful to determine the type of a variable (number, string, boolean). WebThen, we practiced some examples to JavaScript check for null with the falsy, typeof operator, null trap, null alternatives to use, null or undefined, and using the circle class example. Lastly, we reviewed some of the common questions that are asked regarding JavaScript null function.

Optional chaining (?.) - JavaScript MDN - Mozilla …

WebIf the purpose of the if statement is to check for null or undefined values before assigning a value to a variable, you can make use of the Nullish Coalescing Operator. According to the data from caniuse, it should be supported by around 85% of the browsers(as of January … it\u0027s going to the circus disney

How to check if an array is empty, NULL, or undefined in ...

WebOct 25, 2011 · String.isNullOrEmpty = function (value) { return ! (typeof value === "string" && value.length > 0); } This checks if the type of the value is "string" (and thus non-null and not undefined), and if it is not empty. If so, it is not null or empty. Note that this returns true for non-string inputs, which might not be what you want if you wanted to ... WebApr 13, 2024 · To use null and undefined effectively in your JavaScript code, it is essential to follow best practices: Always initialize variables when declaring them to avoid assigning them the undefined value. Use null intentionally to represent the absence of a value when needed. Use strict equality (===) to check for null or undefined values to avoid ... WebPrimitive Data. A primitive data value is a single simple data value with no additional properties and methods. The typeof operator can return one of these primitive types:. string; number; boolean; undefined it\u0027s going to the circus