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?
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7 Answers
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
Comments
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();
Comments
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();
3 Comments
Ben
OK well if I downvoted all the
evals I'd take a big hit, that's not fair for you. Removing.
Chamila Chulatunga
@Steve, I've made some edits to address some of your concerns. Firstly, I'm pointing out that eval is not recommended, and secondly, I have taken down the w3schools link. Nonetheless they asked a question and I'm providing an answer - I don't know if for some reason they really, really can't avoid having the function as a string, so at least this gives them an option
Ben
Noted. I removed it 6 minutes ago :)
WARNING: THIS IS A HORRIBLE PRACTICE! DO NOT DO THIS!
eval(runThis);
once you escaped your inner quotes properly.
Comments
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);
Comments
code = "alert('test');";
eval(code);
Comments
eval(runThis);
But it's not recommended. Just remember eval() is evil.
