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Calling a function from a string stored in a variable can be done in multiple ways in JavaScript. The most common approaches are using the window object (for global functions), object property access, and the eval() function (though not recommended). This tutorial will guide you through different methods to execute a JavaScript function using its name as a string. Using the window Object Method The window object contains all global functions and variables. You can access any global function by treating the function name as a property of the window object. Syntax var functionName ... Read More
The JavaScript eval() function executes a string as JavaScript code. While powerful, it's generally discouraged due to performance and security concerns. Syntax eval(string) Parameters string: A string representing a JavaScript expression, statement, or sequence of statements. Return Value Returns the completion value of evaluating the given code. If the completion value is empty, undefined is returned. Basic Example var a = 30; var b = 12; ... Read More
The (function() { } )() construct is an immediately invoked function expression (IIFE). It is a function that executes immediately upon creation, without needing to be called separately. Syntax (function() { // code })(); The first pair of parentheses converts the function declaration into an expression: (function(){...}) The second pair of parentheses immediately invokes that function expression. Basic Example (function() { console.log("IIFE executed immediately!"); })(); console.log("This runs after IIFE"); IIFE executed immediately! This runs after IIFE ... Read More
In this tutorial, we will learn to check whether a JavaScript function is defined before calling it. If you call an undefined function, JavaScript throws a ReferenceError with the message "function is not defined." To avoid this error, you can check whether the function exists before calling it. We'll explore three different approaches to accomplish this. Using the typeof Operator The typeof operator returns the data type of a variable or function. When used with a function name, it returns 'function' if the function is defined, or 'undefined' if it's not. Syntax let isFunction ... Read More
The function* declaration defines a generator function that returns a Generator object. Unlike regular functions, generators can pause execution with yield and resume later, making them powerful for controlling program flow and creating iterators. Syntax Generator functions can be declared with function* in three equivalent ways: function* myFunction() {} // or function *myFunction() {} // or function*myFunction() {} How Generator Functions Work When called, a generator function doesn't execute immediately. Instead, it returns a generator object with methods like next() to control execution step by step. Basic Example ... Read More
When developing or debugging web applications, finding JavaScript function definitions in Chrome is essential. Chrome provides multiple methods to locate functions quickly and efficiently. This tutorial covers three primary methods for finding JavaScript functions in Google Chrome: Using Developer Tools Sources Panel Using Inspect Element Using View Page Source Using Developer Tools Sources Panel The Developer Tools Sources panel is the most powerful method for finding and debugging JavaScript functions. Steps to Use Developer Tools Step 1: Open Developer Tools ... Read More
The purpose of wrapping JavaScript files in anonymous functions is to create a namespace and control the visibility of member functions. It wraps the code inside a function scope and decreases clashing with other libraries. This is what we call Immediately Invoked Function Expression (IIFE) or Self Executing Anonymous Function. Syntax Here's the basic IIFE syntax: (function() { // code })(); As you can see above, the first pair of parentheses converts the code inside into an expression. The second pair of parentheses immediately calls the function that resulted from the ... Read More
In this tutorial, we will learn to find out the caller function in JavaScript. The function is the reusable code, and users can call it from anywhere. But sometimes, they need to know who is the caller function to perform some operation. For example, suppose that we can call any single function from another 2 to 3 functions, and we need to perform some operation according to the caller function. Users can understand this scenario by the below code example. function func3() { if (caller is func2()) { ... Read More
A namespace is a programming concept that gives identifiers (names of types, functions, variables, etc.) scope to avoid name conflicts. JavaScript doesn't have built-in namespace support, but we can simulate namespaces using objects to organize code and prevent variable name collisions. In modern web applications that use multiple libraries and components, namespaces help avoid confusion and conflicts in code. This tutorial covers how to implement namespaces in JavaScript using different approaches. Object Literal Notation The most common way to create namespaces in JavaScript is using Object Literal Notation. This approach creates a global object that contains all ... Read More
The exclamation mark (!) before a function in JavaScript is used to create an Immediately Invoked Function Expression (IIFE). It transforms a function declaration into an expression that can be executed immediately. How It Works The ! operator has lower precedence than the parentheses (), so the function executes first, then the ! operator applies to its return value: !function() { console.log("IIFE executed!"); }(); IIFE executed! Return Value Behavior Since functions return undefined by default, the ! operator converts this to true: let result1 ... Read More