They are not equivalent. The first will execute the block following theifstatement ifmyVaristruthy(i.e. evaluates totruein a conditional), while the second will execute the block ifmyVaris any value other thannull. The only values that are not truthy in JavaScript are the following (a.k.a...
In JavaScript, undefined is the default value for variables that have been declared but not initialized. On the other hand, null is an intentional assignment that explicitly indicates the absence of a value. Methods to Check if a Variable is Undefined Using typeof Operator Using Strict Equality...
Check If Object-LikeWrite a JavaScript program to check whether a value is object-like. Check whether the provided value is not null and its typeof is equal to 'object'.Check if the provided value is not null and its typeof is equal to 'object'....
}// ✅ Check if nullif(message ===null) {console.log('variable is null'); }// ✅ Check if value is NOT equal to null and undefinedif(message !==undefined&& message !==null) {console.log('variable is NOT undefined or null'); }// ✅ Check if value is equal to null or un...
Since a is undefined, this results in: Null or undefined value! Though, we don't really know which one of these is it. If we were to use the strict operator, which checks if a is null, we'd be unpleasantly surprised to run into an undefined value in the console.log() statement...
Here we missed if the value of 'a' is null: constobj = {a:null}constexisting =typeofget(obj,'a') !== undefined//false, because typeof null === 'object' To solve the problem we can actully using get(obj,'a')!=null//double equals null checks both null and undefined cases...
13 document.getElementById("output").innerHTML = "Sting has some Value"; 14 } 15 } 16 Run Output of Js Check if string is emptyExample 2 : React check if string is null or empty In this second example of this tutorial, we use React JS to check if a string is empty or null u...
0 - This is a modal window. No compatible source was found for this media. texttexttexttexttext=''-- nil or empty string is considered as trueifnottextortext==''thenprint(text,"is empty.")elseprint(text,"is not empty.")endtext='ABC'ifnottextortext==''thenprint(text,"is empty."...
Ensure the value is notundefinedornullusingArray.prototype.includes(). Compare theconstructorproperty on the value withtypeto check if the provided value is of the specifiedtype. constis=(type,val)=>![,null].includes(val)&&val.constructor===type;// Examplesis(Array,[1]);// trueis(ArrayBuff...
Check if a Value IsNaNby Using a Comparison Operator in JavaScript The following method is even faster than the ones detailed above, and it also requires less code. On the other hand, it is a bit more confusing, not to mention that it may prove to be hard to maintain and document prop...