如何在 Javascript 中将参数传递给基于 function 的 eval

Question

I am storing function body in string with function name.

function fnRandom(lim){
    var data=[];
    for(var i=0;i<lim;i++)
    {
        data=data.concat(Math.floor((Math.random() * 100) + 1));
    }
return data;
}

After selecting the functionName from a drop down I use eval to execute function body.

JSON.stringify(eval(this.selectedFunction.body));

I want to pass 'lim' to this execution or can I use functionName as initiating point for execution somehow?

Answer 1

Use Function constructor

 var body = "console.log(arguments)" var func = new Function( body ); func.call( null, 1, 2 ); //invoke the function using arguments

with named parameters

 var body = "function( a, b ){ console.log(a, b) }" var wrap = s => "{ return " + body + " };" //return the block having function expression var func = new Function( wrap(body) ); func.call( null ).call( null, 1, 2 ); //invoke the function using arguments

Answer 2

Eval evaluates whatever you give it to and returns even a function.

var x = eval('(y)=>y+1');
x(3) // return 4

So you can use it like this:

var lim = 3;
var body = 'return lim+1;';
JSON.stringify(eval('(lim) => {' + body + '}')(lim)); //returns "4"

Another way using Function:

var lim = 3;
JSON.stringify((new Function('lim', this.selectedFunction.body))(lim));

Answer 3

You can use the Function object.

 var param1 = 666; var param2 = 'ABC'; var dynamicJS = 'return `Param1 = ${param1}, Param2 = ${param2}`'; var func = new Function('param1', 'param2', dynamicJS); var result = func(param1, param2); console.log(result);

Answer 4

I'm using vuejs, so the code will be like this

getTargetfunction(funcN, o_id, i_id) {
            console.log(funcN, o_id, i_id);
            const x = o_id;
            const y = i_id;
            eval("this." + funcN + "(x,y)");
        },

in the developer mozilla eval()

Indirect eval works in the global scope rather than the local scope, and the code being evaluated doesn't have access to local variables within the scope where it's being called.

  function test() {
  const x = 2;
  const y = 4;
  // Direct call, uses local scope
  console.log(eval("x + y")); // Result is 6
  console.log(eval?.("x + y")); // Uses global scope, throws because x is undefined
}