JavaScript Function Generator

Function generators, introduced in ECMAScript 6 (ES6), are a unique feature of JavaScript that allows developers to create iterators and control the flow of execution in a more sophisticated manner. Unlike regular functions, generators allow you to pause and resume their execution, making them particularly useful for asynchronous programming, dealing with large datasets, and simplifying complex algorithms.

In the below PDF we discuss about Javascript Function Generator in detail in simple language, Hope this will help in better understanding.


Creating a Generator Function:

To create a generator function, we use the function* syntax. This syntax sets the stage for a function with the ability to pause and resume. Inside the generator function, the keyword yield is used to pause the execution and produce a value. Let’s look at a simple example:

function* myGenerator() {
yield 1;
yield 2;
yield 3;
const generator = myGenerator();
console.log(; // { value: 1, done: false }
console.log(; // { value: 2, done: false }
console.log(; // { value: 3, done: false }
console.log(; // { value: undefined, done: true }

In this example, the generator function myGenerator produces a sequence of values (1, 2, 3) using the yield keyword. The method is then used to advance the execution of the generator, producing the next value in the sequence.

Benefits of Function Generators:

  • Asynchronous Code Simplification: Generators provide an elegant solution for handling asynchronous code, making it easier to read and maintain.
  • Lazy Evaluation: Generators enable lazy evaluation, allowing developers to generate values on-demand, potentially saving computational resources.
  • Stateful Functions: Generators maintain their state between calls, making them suitable for scenarios where state persistence is necessary.
  • Error Handling: Generators can be used for structured error handling, improving the robustness of the code.

Related Question

A JavaScript Function Generator is a special type of function that allows you to pause its execution using the yield keyword, enabling the creation of iterators and asynchronous operations.


The yield keyword is used to pause the execution of the generator function and produce a value to the caller. It allows the generator to be paused and later resumed, maintaining its state.

Certainly! Here’s an example of a generator that produces an infinite sequence of numbers:

Yes, generators are often used with asynchronous programming to simplify the syntax. By yielding promises and using asynchronous functions, you can write asynchronous code that looks more like synchronous code, making it easier to understand and maintain.


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