Question

I have never encountered a situation where I needed eval().

Often times, people say that the [] property accessor makes eval() redundant.

Actually, isn’t the execution of a pain statement exactly the same thing as pushing it as an argument into the eval() function. What is it actually used for?

Can you provide examples of when it might be useful to use eval()?

Answer 1

eval is something of a hybrid between an expression evaluator and a statement executor. It returns the result of the last expression evaluated (all statements are expressions in Javascript), and allows the final semicolon to be left off.

Example as an expression evaluator:

foo = 2;
alert(eval('foo + 2'));

Example as a statement executor:

foo = 2;
eval('foo = foo + 2;alert(foo);');

One use of JavaScript’s eval is to parse JSON text, perhaps as part of an Ajax framework. However, modern browsers provide JSON.parse as a more secure alternative for this task.

source

With that in mind the only real reason I can see you wanting to use eval() is for executing user input.. but that leads to serious security risks… so in short I would say eval() (in javascript at least) has become a mute function; replaced by the many specific functions that would have invoked you to use eval() in the past.

Another idea.
You could possibly use it to execute pure js being returned by ajax

your server could pass back a string containing “alert(‘hello world’);” and you could eval(returnData);.