I have a function that can accept any number of arguments...
const getSearchFields = () => {
const joined = arguments.join('/');
};
I want a string of all the arguments being passed to the function joined with the / character. I keep getting this error:
args.join is not a function
Can someone please tell me what I'm doing wrong?
arguments is a pseudo-array, not a real one. The join method is available for arrays.
You'll need to cheat:
var convertedArray = [];
for(var i = 0; i < arguments.length; ++i)
{
convertedArray.push(arguments[i]);
}
var argsString = convertedArray.join('/');
Similar to other posts, you can do the following as shorthand:
var argsString = Array.prototype.join.call(arguments, "/");
As all said above, the arguments object is not really an array, but you can apply array functions directly, by accessing the Array.prototype and executing them with apply or call to change the context:
var argsString = Array.prototype.join.call(arguments, '/');
Edit: Since the original question asked almost 9 years ago was updated to use ES6 syntax, I feel the need to provide an ES6 answer now the language provides native constructs to handle this kind of situations.
The ES6 standard introduces the spread operator, which you can easily use to receive the arguments as an array object, for example:
function sum(...numbers) {
return numbers.reduce((sum, value) => sum + value);
}
console.log(sum(1,2,3,4)); // 10Applied to your example:
const getSearchFields = (...fields) => {
const joined = fields.join('/');
};
You can also use the spread operator to do function calls, let's say you have an array, and you want to call a function, passing each element of the array as an argument of the function call, now you can simply:
function sum(a, b, c, d) {
return a + b + c + d;
}
var array = [1, 2, 3, 4];
console.log(sum(...array)); // 10Also you can expect some arguments and have the rest of the arguments passed as the last parameter defined:
function processList(first, ...rest) {
// ...
}
And there are more uses of the spread operator that go beyond the scope of this question, for example object copying, spreading arrays in arrays, etc...
If you are using jQuery 1.2+, you can use $.makeArray():
Convert an array-like object into a true JavaScript array.
From the example in the question, just use this line
var args = $.makeArray(arguments);
arguments is not really an array.
try this:
var args = [].splice.call(arguments,0);
var argsString = args.join('/');
The problem is that arguments is an array-like object (it has numbered properties mapping to the passed arguments and a length property), but it actually isn't an array.
In the old days, you could make it into a real array with Array.prototype.slice.call(arguments) (among other methods).
However, we're a bit luckier these days (depending on your supported platforms of course). You can either do...
const getSearchFields = (...args) => {
Array.isArray(args); // true
};
...or...
const getSearchFields = () => {
const args = Array.from(arguments);
Array.isArray(args); // true
};
The first example is preferred because...
arguments is a magic variable (it's not defined explicitly, so where did it come from?)'use strict')
arguments is not a JavaScript array; it's a special object that doesn't have a join method.
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values.join is not a function in the file http.es5.js Angular 4
You have to make assignment to a variable for it to work.
var a = ['Wind', 'Rain', 'Fire'];
var myVar1 = a.join();
var myVar2 = a.join(', ');
var myVar3 = a.join(' + ');
var myVar4 = a.join('');
