Finishing up Calculator App: eval(), new Function, or other alternative for evaluation?

JavaScript
1

Hello everyone. I am finishing up my Calculator app, and I’m wondering how should I approach problem of evaluating equations. Everything other is in place: writing digits, operators, brackets and decimals work fine.

How should I approach evaluation of equation? My app writes equations as a string. I’ve looked up eval() function, but learned that it’s very unsafe and should not be used.

BUT, there is other simple alternative - using new Function.

let operation = "2 * 5 + 10"

let evaluation = Function("return " + operation)()

console.log(evaluation) // logs correct result: 20

What do you think about Function method? Is it safer than eval(), or should I write my own way from scratch?

2

eval is fine as long as you control the input. Which you do in this case.

It is unsafe if it accepts input from untrusted sources.

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