如何运行存储在变量中的javascript函数？

Question

I have a variable with instructions inside it, such as:

runThis= "alert(); if(1>2) { alert("NO WAY");}";

How do I run the code inside runThis?

Answer 1

eval(runThis);

But you shouldn't write code this way, it is difficult to manage.

Do it like this instead :

runThis= function () {
  alert(); 
  if(1>2) { 
    alert("NO WAY");
  };
}

then just call runThis

Answer 2

The dirty way to do this would be

eval(runThis);

This is, however, not reccommended at all.

Alternatively, wrap it in a function

runThis = function(){ 
  // statements go here
}

And then you can call it runThis();

Answer 3

If you really want to do this kind of thing, you can use the eval() function:

eval(runThis);

However this is not a recommended approach as it can lead to all kinds of difficult to diagnose bugs and errors

A better approach is to write a proper function with the code you wish to execute, and then assign it to a variable and invoke it via the variable:

//Assign function to variable
runThis = function(){ 
  alert();
  if(1>2) {
    alert("NO WAY");
  };
}

//Later, invoke the function
runThis();

Answer 4

code = "alert('test');";
eval(code);

Answer 5

WARNING: THIS IS A HORRIBLE PRACTICE! DO NOT DO THIS!

eval(runThis);

once you escaped your inner quotes properly.

Answer 6

eval(runThis);

But it's not recommended. Just remember eval() is evil .

Answer 7

Eval will execute a string but you would be better off defining run this as follows. And call it like any function.

var runthis = function(){
     //code  here
}

But if you need to execute a string call eval.

eval(runthis);