CODEWITHSUNDEEP
node.jseval
Doc_failure
Doc_failure

Reputation: 94

is this use of eval in a node server a bad idea?

I want to create an object dynamically in node. To do that i used a code like this. Is this use of eval in a node server a bad idea?

var a1 = require(./a1.js),
    a2 = require(./a2.js),
    ...
    aN = require(./aN.js);

    function createObj(pObjName, pObjValue){
        var tmp = new eval(pObjName)(pObjValue);
        //where pObjName is a1 or a1 or .... or aN
    }

Upvotes: 0

Views: 92

Answers (3)

Patrick Roberts
Patrick Roberts

Reputation: 51866

If you want to save yourself the time of declaring all of those dependencies, you could even write a function without using eval that handles the case even more efficiently:

function createObj(pObjName, pObjValue) {
  var tmp = new (require('./' + pObjName))(pObjValue);
  // ...
}

Please note that this is only safe if createObj() is guaranteed to be invoked with a pObjName that is what you expect, otherwise you'll need to validate it first, possibly something like this:

function createObj(pObjName, pObjValue) {
  if (!/^a\d$/.test(pObjName)) {
    throw new TypeError('invalid name')
  }

  var tmp = new (require('./' + pObjName))(pObjValue);
  // ...
}

Upvotes: 0

robertklep
robertklep

Reputation: 203286

From what you're showing, there's no need to use eval:

const Classes = {
  a1 : require('./a1'),
  a2 : require('./a2'),
  ...
};

function createObj(pObjName, pObjValue){
  var tmp = new Classes[pObjName](pObjValue);
  ...
}

Upvotes: 3

Gekkie
Gekkie

Reputation: 1046

Seems like you want to create objects with a set of properties?

You might want to look at the Object.create()-method

Upvotes: 1

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