Leveraging the power of AngularJS to run JavaScript functions saved as strings

Question

Leveraging the power of AngularJS to run JavaScript functions saved as strings

Is it possible to dynamically inject JavaScript code that is stored in a string into AngularJS controllers?

var dynamicJS = "function DoSomething(value){var x = 1+1  return 2;}"

I need to inject the above function dynamically into my AngularJS controller and have it executed when there is a selection change in a drop-down menu. The values in the drop-down are bound to the AngularJS controller. Each row of data may require a different JavaScript function, which is determined by application configuration. While I am aware of using $eval, I am looking for better approaches if they exist.

Does anyone have any suggestions or ideas on how to achieve this?

_{Note: Using AngularJS v1.4.5}

javascript angularjs

Answer 1

Answer №1

There are various methods to accomplish this task.

Using a Function Object

To achieve this, you can create a Function by passing the necessary argument (such as value) and defining the functionBody:
```
var dynamicJS = "var x = 1+1;  return 2;"
var DoSomething = new Function("value", dynamicJS );
```
Using eval()

Another approach is to use eval(), although it is considered risky:
```
var dynamicJS = "function DoSomething(value){var x = 1+1  return 2;}"
eval(dynamicJS);
```
If your application is internal and isolated from external influences, this method may suffice. However, caution is advised, as highlighted below.

Be Cautious

The MDN documentation regarding eval() emphasizes the risks associated with its usage:

Avoid Unnecessary eval() Calls

_{eval() is a powerful yet dangerous feature that executes code within the caller's context. If the input supplied to eval() is tampered with malicious intent, it could lead to execution of harmful code on the user's device with the permissions granted to your application or extension. Additionally, third-party scripts can access the scope in which eval() was invoked, potentially enabling security vulnerabilities not present when using a similar approach with Function.}

_{eval() also tends to be slower compared to alternative techniques, as it requires invoking the JavaScript interpreter every time, unlike other optimized constructs supported by modern JavaScript engines.}

_{For most common scenarios, there exist safer and more efficient alternatives to eval().} ²

Below, you'll find a demonstration showcasing these methodologies in action. Click on the respective buttons to observe their output in the console.

var dynamicJS = "function DoSomething(value){var x = 1+1;  return 2;}"
var functionBody = "var x = 1+1;  return 2;";
document.addEventListener('DOMContentLoaded', function() {
  document.getElementById('eval').addEventListener('click', function() {
    eval(dynamicJS);
    console.log('DoSomething(3) -> ',DoSomething(3));
  });
  document.getElementById('function').addEventListener('click', function() {
    var dynamicFunction = new Function("value", functionBody);
    console.log('dynamic function(3) ->',dynamicFunction(3));
  });
});

<button id="eval">click to eval</button>
<button id="function">click to use Function</button>

¹

²_{https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval#Don't_use_eval_needlessly!}

Answer 2

There are various methods to accomplish this task.

Using a Function Object

To achieve this, you can create a Function by passing the necessary argument (such as value) and defining the functionBody:
```
var dynamicJS = "var x = 1+1;  return 2;"
var DoSomething = new Function("value", dynamicJS );
```
Using eval()

Another approach is to use eval(), although it is considered risky:
```
var dynamicJS = "function DoSomething(value){var x = 1+1  return 2;}"
eval(dynamicJS);
```
If your application is internal and isolated from external influences, this method may suffice. However, caution is advised, as highlighted below.

Be Cautious

The MDN documentation regarding eval() emphasizes the risks associated with its usage:

Avoid Unnecessary eval() Calls

_{eval() is a powerful yet dangerous feature that executes code within the caller's context. If the input supplied to eval() is tampered with malicious intent, it could lead to execution of harmful code on the user's device with the permissions granted to your application or extension. Additionally, third-party scripts can access the scope in which eval() was invoked, potentially enabling security vulnerabilities not present when using a similar approach with Function.}

_{eval() also tends to be slower compared to alternative techniques, as it requires invoking the JavaScript interpreter every time, unlike other optimized constructs supported by modern JavaScript engines.}

_{For most common scenarios, there exist safer and more efficient alternatives to eval().} ²

Below, you'll find a demonstration showcasing these methodologies in action. Click on the respective buttons to observe their output in the console.

var dynamicJS = "function DoSomething(value){var x = 1+1;  return 2;}"
var functionBody = "var x = 1+1;  return 2;";
document.addEventListener('DOMContentLoaded', function() {
  document.getElementById('eval').addEventListener('click', function() {
    eval(dynamicJS);
    console.log('DoSomething(3) -> ',DoSomething(3));
  });
  document.getElementById('function').addEventListener('click', function() {
    var dynamicFunction = new Function("value", functionBody);
    console.log('dynamic function(3) ->',dynamicFunction(3));
  });
});

<button id="eval">click to eval</button>
<button id="function">click to use Function</button>

¹

²_{https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval#Don't_use_eval_needlessly!}

Answer 3

Answer №2

It seems like the most straightforward approach would involve parsing the String and utilizing the function constructor.

One possible implementation could look something like this:

var PerformAction = new Function('input', 'let result = input * 2; return result;');

Answer 4

It seems like the most straightforward approach would involve parsing the String and utilizing the function constructor.

One possible implementation could look something like this:

var PerformAction = new Function('input', 'let result = input * 2; return result;');

Answer 5

Answer №3

Why not give this a shot:

function customFunc(data){
    var info = data.hasOwnProperty('info') ? data.info : undefined;
    console.log(info);
}

var functionInput = "customFunc({ info: 'example' });",
    Generator = new Function(functionInput);

Generator();

I haven't actually tested it myself... but using this method can help you avoid utilizing eval().

For more details, check out the Function object documentation.

Answer 6

Why not give this a shot:

function customFunc(data){
    var info = data.hasOwnProperty('info') ? data.info : undefined;
    console.log(info);
}

var functionInput = "customFunc({ info: 'example' });",
    Generator = new Function(functionInput);

Generator();

I haven't actually tested it myself... but using this method can help you avoid utilizing eval().

For more details, check out the Function object documentation.

Leveraging the power of AngularJS to run JavaScript functions saved as strings

Answer №1

Using a Function Object

Using eval()

Be Cautious

Avoid Unnecessary eval() Calls

Answer №2

Answer №3

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