JavaScript Define a Function to Check If a Variable is a String 6 7 8 9 // Defining a function 10 function isString(myVar) { 11 return (typeof myVar === 'string'); 12 } 13 14 // Sample variables 15 var x = 10; 16 var y = true; 17 var z = "...
A variable that is declared but not assigned a value will automatically have the value undefined. Below is the sample code let name; console.log(name); // undefined 2. Function Parameters Not Provided If a function is called without supplying arguments for all of its parameters, the missing...
Alternatively, it can also be used as typeof() method in JavaScript.Syntax:typeof(variable); Example 1:str = "This is my place."; if (typeof str == String) { console.log('The variable is a String.'); } else { console.log('The variable is not a String.'); } ...
Using isArray() Method To check if a variable is an array in JavaScript, we have used isArray() method. It returns a boolean value as result, either true or false. We have used two div elements to display the array and output using getElementById() and innerHTML property. We have al...
The customisString()JavaScript function in the following example will returntrueif the variable is a string otherwise returnfalse. Let's try it out and see how it works: Example Try this code» // Defining a functionfunctionisString(myVar){return(typeofmyVar==='string');}// Sample varia...
JavaScript is a versatile language, but it can sometimes lead to confusion, especially when dealing with variables. One common issue developers face is determining whether a variable is undefined. This can happen for various reasons, such as a variable not being initialized or a function not retur...
Checking if Boolean Is Primitive or ObjectA boolean literal (i.e. true or false) is a primitive. You can check this using the custom isPrimitive() function: console.log(isPrimitive(true)); // true console.log(isPrimitive(false)); // true ...
if(!Array.isArray){Array.isArray=function(arg){returnObject.prototype.toString.call(arg)==='[object Array]';};} #Other Ways using Lodash or Underscore If you're using an external library, they also have some built-in methods too 👏 ...
JavaScript provides several ways to check if a variable is a string. One of the most common methods is to use thetypeofoperator, which returns the type of a variable. For example, the following code checks if a variable named “myVar” is a string: ...
Javascript Boolean Type Introduction Using the typeof operator, we can check the datatype of a variable. If the variable is a Boolean value, typeof will return the string 'boolean'. Copy vara =Boolean(true);varb = false;//www.java2s.comvarc ="";vard = newDate();if(typeofa ==='...