Qfyilyi

I have this code

(function(data){

    this.init=function(){

        console.log("Hello world");

    };

    this.init();

});

I wan to call the anonymous function from external code, without self execution. Can anyone help whit this?

You would have to attribute the anonymous function to a variable in order to get a reference to it and then be able to call it like the code bellow:

var myFunc = (function(data){...})

However, assuming you don't have control over the javascript to which you are trying to do it, you would have to evaluate the code as described by MDN in this chapter and build the previous expression.

UGLY CODING PRACTICES ALERT: this practice I'm about to propose is not at all a good practice, evaluating javascript code at runtime is not good and should be avoided unless it is extremely necessary. Having said that, and you still think you need to do this, follow the instructions bellow (and suit your self).

First, you have to do an HTTP request to your javascript file and get its contents. Then, you can create an expression and evaluate it like bellow supplying the code obtained from the request (myCodeFromHttpRequest).

eval('var myFunc = ' + myCodeFromHttpRequest);

myFunc();

This way you somehow mock what you would be trying to do if you had control over the code.

But, using eval is bad practice, as MDN suggests, you can evaluate it to a function instead, so that it will create an isolated scope preventing javascript to do the global check for new variables and preventing your code from injecing insecure garbage on the global scope as you are adding a new piece of code on the running program.

var myFunc = Function('return ' + myCodeFromHttpRequest)();

myFunc();

That is basically creating a function that returns your anonymous function and self executing it to produce the value and assign it to the myFunc var.

You final solution would be something like this:

you can use $.ajax or a different HTTP client if you don't support fetch

fetch('my-script.js').then(async(res) => {



    var myCodeFromHttpRequest = await res.text();

    var myFunc = Function('return ' + myCodeFromHttpRequest)()



    myFunc();

});

Working snippet:

// fetch('my-script.js').then(async(res) => {



    var myCodeFromHttpRequest = //await res.text();

      // mocked code in order to simulate the request

      '(function(data){' +

      '    this.init=function(){' +

      '        console.log("Hello world");' +

      '    };' +

      '    this.init();' +

      '});';

    

    var myFunc = Function('return ' + myCodeFromHttpRequest)()



    myFunc();

//});