How to Auto Apply Coupons - Chrome Extension - Run function between page loads

This video demonstrates how to run a JavaScript function across multiple pages using local storage. The example is a coupon autofill function that persists its state (which coupons have been checked, the best coupon found) between page reloads, even if the page requires a refresh after each coupon check. The code uses local storage to store and retrieve the function's progress, allowing it to resume where it left off after each page load. The function is designed to be adaptable to various website structures by using a configurable selector object. This segment details the mechanism by which the function continues its execution across page loads. It explains how the function checks local storage upon loading to determine if it's already running and resumes from where it left off, or starts anew if it's a fresh invocation. The explanation clarifies the function's state management.This segment focuses on the design considerations for making the function adaptable to various websites. It highlights the importance of using flexible selectors and handling different website structures and checkout processes to ensure broad compatibility. The discussion emphasizes the importance of robust design for extensibility.This segment addresses the challenges of handling diverse website checkout processes. It explains how the function accommodates variations in coupon application methods (button clicks, Enter key presses, page reloads), wait times, and data retrieval methods, showcasing the function's adaptability to different website designs.This segment provides a detailed explanation of the selector object and its properties. It breaks down each property's purpose, including cost field, coupon type, wait time, and others, clarifying how these properties configure the function's behavior for different websites. The explanation provides a clear understanding of the function's configuration parameters. This segment showcases a practical demonstration of the coupon autofill function without page reloads. The function iterates through an array of coupon codes, applies each one, checks the order total, and identifies the coupon providing the best discount. The demonstration visually illustrates the function's core functionality.This segment demonstrates the function's behavior when page reloads are required after each coupon application. The video shows how the function continues to operate correctly even with page refreshes, highlighting the role of local storage in maintaining the function's state across these reloads. This segment details the core logic for applying coupons, including comparing the discounted price to the current best deal and updating the basket value accordingly. The process ensures data consistency by converting values to floats for accurate comparisons, handling potential pence or cents in the basket value. This section explains how the system prevents infinite loops by tracking checked coupons and avoiding redundant checks. The process involves pushing checked coupons onto an array and updating the coupon check object, ensuring each coupon is processed only once.This segment describes the process of updating the coupon check object, converting it to a JSON string, and removing the current coupon from local storage after processing. It also clarifies the purpose of a test section mimicking server communication.This portion explains how the main function is recursively called after each coupon check to ensure continuous monitoring for new deals upon page load. The recursive call is explained, highlighting the mechanism for continuous coupon checking. This segment visually demonstrates the function's progress using the browser's developer tools. It shows how the function updates local storage with its state, including checked coupons and the current coupon being processed, providing a visual representation of the function's internal workings. The visual demonstration enhances understanding of the function's state management.This segment begins the code walkthrough, focusing on the selector object and how coupon data is handled. It explains how the function is designed to be adaptable to different websites by using a configurable selector object and how coupon data might be integrated from external sources like databases. The explanation clarifies the function's modular design.This segment continues the code walkthrough, explaining the event listener that triggers the function and the function's initialization process. It details how the function starts, sets up local storage, and handles initial values. The explanation clarifies the function's initiation and event handling.This segment focuses on the `runCheck` function and how it handles different statuses ("start" and "continue"). It explains how the function determines whether to start a new check or continue a previous one, based on the status parameter and local storage. The explanation clarifies the function's state management.This segment explains the initial setup within the `runCheck` function, including setting local storage, retrieving the initial basket value, and initializing variables for tracking the best deal and checked coupons. The explanation clarifies the function's initialization steps.This segment details how the function manages local storage, storing and retrieving the function's state. It explains the conversion of objects to JSON strings for storage and retrieval, ensuring data compatibility with local storage. The explanation clarifies the function's data persistence mechanism.This segment explains the code for continuing the function's execution after a page reload. It details how the function retrieves its previous state from local storage and resumes its operation, ensuring continuity across page loads. The explanation clarifies the function's state restoration mechanism.This segment explains the core logic for checking coupons. It details how the function iterates through coupons, checks if they've already been checked, and handles cases where the selector object is invalid. The explanation clarifies the function's core coupon-checking algorithm.This segment explains the loop that iterates through the coupons, checking if each coupon has already been checked. It details how the function identifies the next coupon to check and prepares for the next iteration. The explanation clarifies the function's iterative process.This segment explains the code for handling the completion of the coupon checks. It details how the function identifies the best deal, cleans up local storage, and displays the results. The explanation clarifies the function's result handling and cleanup process.This segment explains the `checkCouponStart` function, which handles applying a coupon to the input field and either pressing a button or pressing Enter. It details how the function handles page reloads and waits for the page to update before continuing. The explanation clarifies the function's interaction with the website's interface.This segment explains the `checkCouponEnd` function, which is called after a coupon is applied and the page is updated. It details how the function retrieves the updated basket value and updates the function's state. The explanation clarifies the function's post-application update process.