当我有 function 名称时执行 function 的正确方法

Question

I have a string "Car.run(true)" or "Car.find('window')" , I want to execute the function run or find and also pass respective parameters passed. What is the correct way to do it without using eval ?

I tried to split the string, extracted the function name and parameters using regex but issue is with boolean values(it will a string after extraction).

Can anyone guide me to resolve this blocker?

Answer 1

In javascript land, classes are just objects that can be referenced using dictionary lookup syntax

class Car { run(x) { return x } find(x) { return x }  }
car = new Car()
method_name = 'run'
car[method_name]    # == ƒ run(x) { return x }
car[method_name](1) # == 1

In python land you would need hasattr() and getattr()

Answer 2

You can try simply like below, if you dont want to use eval :

var functionHolder = "Car.run(true)";
var myTmpFunction = new Function(functionHolder);
myTmpFunction ();  //This would invoke

Answer 3

Generally using eval is not a good idea, and this isn't great either but it's a start:

 function Car() { this.run = function(args) { console.log('Running', args) } } const str = "Car.run(true)"; // Get the constructor name and the function with arguments as a string const [ctor, fn] = str.split('.'); // The name of the function without parens const fnName = fn.replace(/\((.+)\)/, '') // Get the argument list of the function const originalArgs = fn.match(/\((.+)\)/) // Clean arguments const args = originalArgs[1].split(',').map(str => str.trim()).filter(Boolean); // Instantiate a new object based on the name const f = new(Function.prototype.bind.apply(window[ctor]))(); // Invoke the function with the arguments f[fnName].apply(f, args) // Running true

General idea comes from the AngularJS source and how it instantiates objects from strings.