Why is my `setTimeout` Function Executing Immediately Instead of After the Delay?

setTimeout Function Invocation Delay Issue

When attempting to implement a 5-second polling mechanism for an HTML value update, users may encounter unexpected behavior where the setTimeout() function is called immediately instead of after the intended delay. This can prevent the desired staggered server requests.

Cause:

The issue stems from the incorrect way the setTimeout() function is being invoked.

Original Code:

setTimeout(GetUsersNumber(), 50000);

Explanation:

In JavaScript, functions can be defined as objects without parentheses. However, to call a function, it must be followed by parentheses. In the original code, the function GetUsersNumber() is being called immediately inside the setTimeout(), rather than being passed as a function reference.

Solution:

To fix the issue, simply remove the parentheses after the function name in the setTimeout() argument:

setTimeout(GetUsersNumber, 5000); // 5 seconds instead of 50

This ensures that setTimeout() captures a reference to the GetUsersNumber function object itself, allowing it to invoke the function when the delay is complete.

The above is the detailed content of Why is my `setTimeout` Function Executing Immediately Instead of After the Delay?. For more information, please follow other related articles on the PHP Chinese website!