In JavaScript, there are various methods available to check if a variable is undefined. Each method has its own use cases and subtle differences. 1. Using typeof Operator The typeof operator can be used to check if a variable is undefined by comparing its type with the string ‘undefined...
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let myVar; if (typeof myVar === "undefined") { console.log("myVar is undefined"); } else { console.log("myVar is defined"); } Output: myVar is undefined In this example, we declare a variable myVar without assigning any value to it. When we check its type using typeof, we ...
how to check SVG type in js SVGSVGElement & SVGElement svg =document.querySelector(`svg`);// <svg class="icon" style="width: 100px; height: 100px;vertical-align: middle;fill: currentColor;overflow: hidden;" viewBox="0 0 1024 1024" ve...
Theisa()function in MATLAB has the following syntax: isOfType=isa(variable,'typeName'); Here,variableis the variable whose type we want to check, and'typeName'is the name of the type we are checking against. The result is a logical value (1for true,0for false) stored in the variable...
Object.prototype.toString.call(variable) === '[object Array]'; 1. This guy is the slowest for trying to check for an Array. However, this is a one stop shop for any type you're looking for. However, since you're looking for an array, just use the fastest method above. ...
What is a null check? In JavaScript, null represents an intentional absence of a value, indicating that a variable has been declared with a null value on purpose. On the other hand, undefined represents the absence of any object value that is unintentional. A null check determines whether a...
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Object.prototype.toString.call(variable) === '[object Array]'; This guy is the slowest for trying to check for an Array. However, this is a one stop shop for any type you're looking for. However, since you're looking for an array, just use the fastest method above. ...
In JavaScript, the assignment of the primitive type will copy the variable value completely, and the assignment of the object (reference) type will copy the reference address. Here are two more frequently asked interview questions to practice your hands ...