Create a function that will convert a parameter to array

Question

I need to create a function, that will parse function parameter of integer to an array list.

So if we call the function like this: sum(1, 4 ,7); then inside of the function 'sum' the arguments variable/keyword will look like this [1, 4, 7]. I need to create a sum function so that it can take any number of arguments and return the sum of all of them.

Here's my code so far:

function sum ([a,b]) {
var arr = [a,b];
var sum =arr.reduce(add, 0);

function add(a, b) {
return a + b;
}
}

I also was trying to so something like this:

function sum ({
  arr[0]: 1;
  arr[1]: 2;
  arr[2]:3;

  var sum =arr.reduce(add, 0);

function add(a, b) {
return a + b;
}
})

but I obviously doing something wrong.

tomision · Accepted Answer · 2016-11-30 13:50:15Z

2

Try this

function sun () {
  return Array.prototype.reduce.call(arguments, function(pre, cur) {
    return pre + cur
  }, 0)
}

This is your need.

answered Nov 30, 2016 at 13:50

tomision

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7 Comments

random_user_name Over a year ago

Explain what you've done. Code only answers are not useful. Also, you've got typos. ALSO, you've baked "add" into this function, which is not what OP requested.

Alice Jarmusch Over a year ago

Thanks, but what is "pre" and "cur" in here? Just an elements of the array?

tomision Over a year ago

@AliceJarmusch this is two of the params of Array.prototype.reduce developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

tomision Over a year ago

@cale_b My mistake @AliceJarmusch you wanna accumulation the params of function sum, but you don't know the count of the params. By the arguments in the function, you can get all the params like Array, but this is not Array. So you should use .call to execute reduce on it.

tomision Over a year ago

@AliceJarmusch In ES6, you shouldn't use arguments in the array, you should use ...args operator get all the params. You can try @Tresdin answer in babel.

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Nina Scholz · Accepted Answer · 2016-11-30 13:58:59Z

0

Just for changing arguments to an array of an array like object, you could use Array.apply.

Comments

Vijayraj · Accepted Answer · 2016-11-30 14:00:09Z

0

var sum =function() {
    var args = [];
    args.push.apply(args, arguments);
    return args.reduce((a,b) => { return a+b}, 0); // ES6 arrow function
}
sum(1,2,3); // return 6

answered Nov 30, 2016 at 14:00

Vijayraj

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1 Comment

JAL Over a year ago

Please elaborate on how this code answers the question.

Lewis · Accepted Answer · 2016-11-30 14:00:32Z

0

Try this ES6 solution.

let sum = (...args) => args.reduce((a, b) => a + b, 0);

You can see the MDN article of rest parameters for more details. It is basically used for retrieving the list of arguments in an array.

edited Nov 30, 2016 at 14:00

answered Nov 30, 2016 at 13:50

Lewis

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2 Comments

Alice Jarmusch Over a year ago

Isn't it just the same as I'm trying to do? As I understand, the only issue here is to convert args to a list, and apply .reduce() to it. And I don't really know what I can do with it.

Lewis Over a year ago

@AliceJarmusch You don't need a function to convert arguments to an array. Rest parameters were designed for this task.

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