javascript - Why does eval() exist?

Question

Many programmers say it is a bad practice to use the eval() function:

When is JavaScript's eval() not evil?

I'd like to take a moment to address the premise of your question - that eval() is "evil"...

Is this eval() dangerous?

Buggy evaled code can violate security properties just as easily as buggy source code...

Why not eval() JSON?

There are a number of ways that your security may be compromised...

Is there ever a good reason to use eval()?

Yes - when there is no other way to accomplish the given task with a reasonable level of clarity... This eliminates 99% of cases where eval is used...

Why is eval unsafe in javascript?

The danger of eval only rears its ugly head when you are serving a script written by alice to user bob for bob's browser to eval...

So why does it exist in the first place?

Answer 1

Because sometimes there is a need. All the same reasons for/against using eval in JavaScript can likely be shared with the use of reflection in Java, for example.

However, I agree with everything you quoted in your question. Many reasons for using it are ill-advised, and best done differently - but sometimes, there is still a need, or it is simply the "best choice" over other available alternatives. (I'd focus on the answers to Is there ever a good reason to use eval()? for additional reasons.)

+1 to your question for good research.