I'm trying to do something like this:
function simpleOperations(operation) {
let myFanction = new Function('a', 'b', 'a ' + operation + ' b');
return myFanction
}
let sum = simpleOperations("+")
let multiplicate = simpleOperations("*")
console.log("your sum is: " + sum(3,7));
console.log("your product is: " + multiplicate(3,7));
and instead of getting:
your sum is: 10
your product is: 21
I'm getting this:
your sum is: undefined
your product is: undefined
Do you have any thoughts on how to fix it? :)
The text body of the function needs to return the value, otherwise your a + b or a * b etc will just be an unused expression.
function simpleOperations(operation) {
let myFanction = new Function('a', 'b', 'return a ' + operation + ' b');
return myFanction
}
let sum = simpleOperations("+")
let multiplicate = simpleOperations("*")
console.log("your sum is: " + sum(3,7));
console.log("your product is: " + multiplicate(3,7));Using Function is an anti-pattern. It's one degree away from eval and there's always a better way to write things, especially considering JavaScript already supports first-class functions -
const add = (a, b) => a + b
const multiply = (a, b) => a * b
console.log("your sum is: " + add(3,7))
console.log("your product is: " + multiply(3,7))your sum is: 10
your product is: 21
If instead you want to access functions using "+" and "*" strings, you can create a simple lookup and throw an Error when a particular operation is not supported -
const operations = {
"+": (a, b) => a + b,
"*": (a, b) => a * b
}
function simpleOperations(op) {
const f = operations[op]
if (f == null)
throw Error(`unsupported operation: ${op}`)
return f
}
const add = simpleOperations("+")
const multiply = simpleOperations("*")
console.log("your sum is: " + add(3,7))
console.log("your product is: " + multiply(3,7))
const divide = simpleOperations("/") // <- not yet implementedyour sum is: 10
your product is: 21
Error: unsupported operation: /
Implementing a simple calculator is a great way to learn how to write your first programming language. If this sort of thing interests you, see this related Q&A.