Avoid using eval() to call function by name with only dynamic string

Question

I have this simple switch block:

function modifyServiceContractView(schema) {
     ...
}

function modifyContactView(schema) {
    ...
}


function addExtraInfoToSchema(defName, schema) {

  switch (defName) {

    case 'ServiceContractView':
      return modifyServiceContractView(schema);
      break;

    case 'ContactView':
      return modifyContactView(schema);
      break;

    default:
      return schema;

  }

}

instead of hardcoding a switch block, it would be nice to just have something like this instead:

function modifyServiceContractView(schema) {
    ...
}

function modifyContactView(schema) {
    ...
}


function addExtraInfoToSchema(defName, schema) {

    return eval('modify' + defName+ '(schema)');

}

is there a better way to do this without eval()?

hopefully my question is clear.

Yes, use an object literal to store your functions.. you can then do func['modify' + defName](schema) — Keith
– Keith, Commented Oct 5, 2016 at 21:22

Barmar · Accepted Answer · 2016-10-05 21:24:53Z

1

Use an object whose keys are the names and values are the functions.

var modifyFuncs = {
    ServiceContractView: modifyServiceContractView,
    ContactView: modifyContactView
};

function addExtraInfoToSchema(defName, schema) {
    if (defName in modifyFuncs) {
        return modifyFuncs[defName](schema);
    } else {
        return schema;
    }
}

answered Oct 5, 2016 at 21:24

Barmar

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Comments

Mike Cluck · Accepted Answer · 2016-10-05 21:25:20Z

1

You could store your functions in an object then access them by name.

var modify = {
  ServiceContractView: function(schema) {
    console.log('ServiceContract', schema);
  },
  ContactView: function(schema) {
    console.log('Contact', schema);
  }
};

function addExtraInfoToSchema(defName, schema) {
  return modify[defName](schema);
}

addExtraInfoToSchema('ServiceContractView', 1);
addExtraInfoToSchema('ContactView', 2);

answered Oct 5, 2016 at 21:25

Mike Cluck

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Comments

trincot · Accepted Answer · 2020-10-23 08:50:22Z

0

Make the functions object properties:

return (f => f ? f(schema) : schema)({
    modifyServiceContractView,
    modifyContactView
}['modify' + defName]);

edited Oct 23, 2020 at 8:50

answered Oct 5, 2016 at 21:25

trincot

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1 Comment

mscdex Over a year ago

window doesn't exist in node. Besides, making them global (in node) is a bad decision and unnecessary.

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