In JavaScript, a value can either be a primitive or an object. Therefore, you can check if a value is a JavaScript primitive (as opposed to being an object) using the following check: !(value instanceof Object) You may see value !== Object(value) as a means to check for prim...
In JavaScript, a variable can be defined, but hold the valueundefined. if(typeofv ==="undefined") {// no variable "v" is defined in the current scope// *or* some variable v exists and has been assigned the value undefined}else{// some variable (global or local) "v" is defined ...
This is a short guide on how to check if a variable or value if an object using JavaScript. In order to do this, we can use thetypeofoperator, which returns the data type of a given value in a string format. Take a look at the following JavaScript snippet: //An example object. va...
JavaScript has a primitive data type called undefined that represents a variable without being assigned. In addition to undefined property, JavaScript has a null value, and both values represent empty values in JavaScript. These often confuse users about whether a variable is undefined or null. In ...
Checks if value is classified as an Array object. constarray=['🍝','🍜','🍲'];constnotArray='not array';_.isArray(array);// true_.isArray(notArray);// false Underscore Returns true if object is an Array. constarray=['🍝','🍜','🍲'];constnotArray='not array';_.isArr...
A variable is calledundefinedif it is declared without being assigned an initial value. Below are multiple ways we can do this in JavaScript. Directly Compare a Variable Withundefinedto Check Undefined in JavaScript varx;if(x===undefined){text='x is undefined';}else{text='x is defined';}...
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Check if a Value is Truthy in JavaScriptWe used the logical NOT (!) operator to check if the myVar variable stores a falsy value. The falsy values in JavaScript are: false, 0, -0, "" (empty string), null, undefined, NaN (Not a number). ...
value trysoundpublished 5.0.0 • 4 years agopublished version 5.0.0, 4 years ago M Q P Maintenance: 2%. Quality: 62%. Popularity: 49%. is-accessor-descriptor Returns true if a value has the characteristics of a valid JavaScript accessor descriptor. accessor check data descriptor get getter...
This is why it’s better to use thetypeofoperator to really check if a value isundefined. × Thetypeofoperator won’t throw an error when you haven’t declared the variable during the checking, but a direct comparison such asy === undefinedwill break your JavaScript application. ...