In JavaScript, we need the wait or delay functionality to pause the execution of a piece of code for a certain period of time in different cases such as animations, time based events, or to synchronize the execution of code across multiple functions or threads.
When creating animations in JavaScript, we often need to wait for a certain amount of time before changing the state of the animation. By using a wait function, we can create a pause in the animation to achieve the desired effect. We might need to delay the execution of a piece of code until a certain amount of time has passed. For example, we might want to show a popup message to a user after they have been on a page for a certain amount of time. In some cases, we might need to synchronize the execution of code across multiple functions or threads. By using a wait function, we can ensure that certain functions are executed in a specific order.
The wait functionality in JavaScript is achieved through non-blocking techniques, such as setTimeout or setInterval. This means that while waiting for the delay to finish, other code can execute. As a result, the wait functionality in JavaScript is often used in conjunction with event-driven programming techniques, such as callbacks or promises.
The setTimeout function in JavaScript is used to delay the execution of a block of code for a specified amount of time, in milliseconds. When you call setTimeout, you pass in two arguments: a function to execute after the delay, and the delay time. The function can be defined inline using an anonymous function, or you can pass in a named function.
The setTimeout function is non-blocking, which means that while waiting for the delay to finish, other code can execute. This is useful for creating animations, for example, where you want to delay the execution of some code to create a pause in the animation.
However, it’s important to note that setTimeout is not a precise timing mechanism. The actual delay time may be longer or shorter than the specified time, depending on various factors such as the load on the CPU and other running processes.
Note that setTimeout is non-blocking, meaning that other code can execute while waiting for the delay to finish. If you need to pause the execution of the entire script, you can use the sleep function, but it is not recommended, as it will freeze the browser tab or node.js process.