Passing Strings to setTimeout: A Question of Necessity

Many developers frown upon the practice of passing strings to setTimeout due to performance concerns, potential security risks, and its deprecated status. However, there may be rare scenarios where this syntax could be beneficial.

The Deprecation Debate

The traditional syntax for setTimeout and setInterval involved passing a string that represented the code to execute. For example:

setTimeout('doSomething(someVar)', 10000);

However, modern JavaScript promotes the use of function references instead:

setTimeout(function() {
    doSomething(someVar);
}, 10000);

The Argument for Strings

The debate arises when considering whether there are any valid reasons to deviate from the recommended syntax. One possible argument could be the desire to access a function or variable that resides in the global scope but might have been overridden locally.

The Case Against Strings

Despite this rationale, the use of strings in setTimeout is strongly discouraged. Global variables can still be accessed through the window object's properties. For instance:

setTimeout(window.doSomething(someVar), 10000);

Historical Tolerance

The allowance of strings as arguments to setTimeout and setInterval is likely rooted in historical factors. Early versions of JavaScript supported only strings. Adding the ability to pass function references was a later addition. To ensure backward compatibility, browsers still allow the string syntax, even though it is deprecated.

Conclusion

While it is technically possible to pass strings to setTimeout in certain cases, the practice is generally not recommended due to the availability of alternative approaches. The use of function references provides improved performance, enhances security, and adheres to modern code guidelines. Therefore, the deprecated string syntax should be avoided for clarity, maintainability, and overall code quality.