Checking this is easy. console.log('value is either null, undefin... Send. An empty array will have 0 elements inside of it. (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 (data) { // do something } Since, in javascript, both null values, and empty strings, equals to false (i.e. If you pass any non-empty string then it will pass the test which is wrong, so for that we have to use Method 2 but to understand Method 2, you should try & test Method 1. method isNullEmpty () to check if a string is null or empty. var myname = document.getElementById("Name").value; You can write a JavaScript form validation script to check whether the required field (s) in the HTML form is blank or not. So letâs check an array is empty or not. }. Blank fields indicate two kinds of values. Company. if (str != null && !str.isEmpty ()) Be sure to use the parts of && in this order, because java will not proceed to evaluate the second part if the first part of && fails, thus ensuring you will not get a null pointer exception from str.isEmpty () if ⦠There are only six falsey values in JavaScript: undefined, null, NaN, 0, "" (empty string), and false of course. It is possible to check for a falsy value in a variable with a simple conditional: if (!variable) { // When the variable has a falsy value the condition is true. a null string str1an empty string str2a string with white spaces str3method isNullEmpty () to check if a string is null or empty But it always returns true for Number type of J... ; A blank String contains only whitespaces, are is neither empty nor null, since it does have an assigned value, and isn't of 0 length. The required object should be passed to the Object.keys (object) then it will return the keys in the object. If you just want to check whether there's a truthy value, you can do: Both null and empty could be validated as follows: