Working with operators from string in JS without 'eval()' or 'new Function()'

Asked Mar 30 '23 at 11:44

Active Mar 30 '23 at 12:19

Viewed 43 times

I got an assignment where a DB has operator conditions (===, <, >, * etc) to use with some accompanying data.

I need to run those conditions in my JavaScript code. What I found around here is usage of eval or the Function constructor, but both have crucial security and performance issues and are not an option for production code in any sense.

Example:

const operatorFromDB = '>'

const param1FromDB = '10'

const param2FromDB = '5'

But running eval('${param1FromDB}${operatorFromDB}${param2FromDB}') is problematic.

So, how do I actually solve this?

edited Mar 30 '23 at 11:49

asked Mar 30 '23 at 11:44

flow24

can you give more context – cmgchess Mar 30 '23 at 11:45
@Teemu added an example in the post. – flow24 Mar 30 '23 at 11:50
@cmgchess added an example. please let me know if you need anything more – flow24 Mar 30 '23 at 11:51
how about using logic like if operator is '>' do param1 > param2 and so on. i meant switch statement or if else – cmgchess Mar 30 '23 at 11:52
A popular way is to create an object with operator methods, like `ops = {'>': (a, b) => a > b}`, then call ex. `ops['>'](3, 2)`. – Teemu Mar 30 '23 at 11:54

Working with operators from string in JS without 'eval()' or 'new Function()'

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