Retrieve JavaScript functions as JSON or text in AngularJS and execute them

Question

Retrieve JavaScript functions as JSON or text in AngularJS and execute them

Currently, I am working on developing an AngularJS application and have come across a particular challenge that needs to be addressed:

After making a web service call, I receive JavaScript code that looks like this:

{ 
 "script":"function foo(a, b) { c = bar(a,b) $scope.c = c } function bar(a,b) { return a+b }"
}

My goal is to invoke the foo(a,b) function in my AngularJS application and have the property c within my $scope reflect the result from the bar(a,b) function.

Is it feasible for the foo(a,b) function to access $scope? What if there are existing functions named foo() or bar() within my application?

I've tried exploring solutions using eval and Function() features in JavaScript. However, I'm uncertain whether those can resolve my issue effectively.

pass function in json and execute

Your assistance or recommendations on this matter would be highly valued :)

Cheers,

Kevin

javascript json angularjs function eval

Answer 1

Answer №1

One way to approach this issue is by reconsidering the structure of your code. It's a cause for concern if you're passing around code as text and then using eval to execute it. It's recommended to refactor your code to use more standard coding practices whenever possible.

Setting that aside, someone inquired about using the eval and Function() capabilities in JavaScript. However, they expressed uncertainty about whether this method would solve their problem effectively.

Indeed, it can work. The eval function operates within the scope where it's invoked, which means any variables created inside will only exist within that specific context or function call unless preserved elsewhere.

For instance:

function evaluate($scope) {
    eval(yourString);
}

This will confine any new variables like 'foo' and 'bar' to the evaluate function itself, ensuring access to the $scope argument only while executing the function.

It's essential to exercise caution when utilizing eval, ensuring the script originates from a trustworthy source.

An important distinction to note is that the behavior of eval changes when indirectly called through a variable instead of directly:

var e = eval;
e(yourString);

In such cases, the evaluation occurs globally rather than within the same local scope. This explains why some opt for unconventional methods like (0,eval)(string) to trigger eval globally, whereas assigning eval to a new variable like globalEval followed by calling globalEval(string) provides better clarity and maintainability.

Answer 2

One way to approach this issue is by reconsidering the structure of your code. It's a cause for concern if you're passing around code as text and then using eval to execute it. It's recommended to refactor your code to use more standard coding practices whenever possible.

Setting that aside, someone inquired about using the eval and Function() capabilities in JavaScript. However, they expressed uncertainty about whether this method would solve their problem effectively.

Indeed, it can work. The eval function operates within the scope where it's invoked, which means any variables created inside will only exist within that specific context or function call unless preserved elsewhere.

For instance:

function evaluate($scope) {
    eval(yourString);
}

This will confine any new variables like 'foo' and 'bar' to the evaluate function itself, ensuring access to the $scope argument only while executing the function.

It's essential to exercise caution when utilizing eval, ensuring the script originates from a trustworthy source.

An important distinction to note is that the behavior of eval changes when indirectly called through a variable instead of directly:

var e = eval;
e(yourString);

In such cases, the evaluation occurs globally rather than within the same local scope. This explains why some opt for unconventional methods like (0,eval)(string) to trigger eval globally, whereas assigning eval to a new variable like globalEval followed by calling globalEval(string) provides better clarity and maintainability.

Retrieve JavaScript functions as JSON or text in AngularJS and execute them

Answer №1

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