How to convert JavaScript Array to elements

Question

I have an Array

var fieldsToFetch = ['name', 'class', 'rollNumber'];

I am using this array into NODE-ORM2 query, in simple words, I am saying to ORM that this are the fields I want to fetch.

Person.find({ surname: "Doe" }).limit(3).offset(2).only("name", "class", "rollNumber").run(function (err, people) {
    // returning only 'name', 'rollNumber' and 'class' properties
    //this is working fine
});

In this code, you can see the .only() function which takes the field names. If I am passing the name here by comma separating then it is working fine but if I do like this

Person.find({ surname: "Doe" }).limit(3).offset(2).only(fieldsToFetch).run(function (err, people) {
    // returning only 'name', 'class' and 'rollNumber' properties
    // not working 

});

I also tried

String(fieldsToFetch ); and fieldsToFetch .toString(); but it converts whole array into a single string. So how can I use this array as a parameter here?

Thankyou.

EDIT

Passing 2 or 3 parameter is not a challenge the main goal is to get all array element as individual elements.

Suren Srapyan · Accepted Answer · 2017-03-15 06:30:17Z

1

Because you pass an array, but it want separate strings, so if you use ES6 you can pass like .only(...fieldsToFetch). This is called spread operator. It gets the array, splits it into items and passes them as separate parameters.

Example

function f(a,b,c){
  console.log(a);
  console.log(b);
  console.log(c);
}

var args = [1,2,3];

f(...args);

I pass the array with the spread operator and it splits the array into separate items and assigns to the parameters in direction from left to right.

edited Mar 15, 2017 at 6:30

answered Mar 15, 2017 at 6:23

Suren Srapyan

68.9k14 gold badges128 silver badges119 bronze badges

Sign up to request clarification or add additional context in comments.

8 Comments

Hikmat Sijapati Over a year ago

but OP needs to put only two elements of array.only("name", "class").

Arpit Kumar Over a year ago

What does ... mean? Is it a kind of operator or you want to say something else?

Suren Srapyan Over a year ago

@ArpitMeena see the link, embedded in answer

Arpit Kumar Over a year ago

@Suren _Srapyan thanks, but it is showing an error SyntaxError: Unexpected token ... and JSHINT is also showing an error: [jshint] 'spread/rest operator' is only available in ES6 (use 'esversion: 6'). (W119)

Suren Srapyan Over a year ago

@ArpitMeena The spread operator needs ES6, but you use older version, you need to pass item by item like .only(fieldsToFetch[0], fieldsToFetch[1])

|

Hikmat Sijapati · Accepted Answer · 2017-03-15 06:35:59Z

0

Try like this..use array.splice() to remove last element from array.Then use ... spread operator:

var fieldsToFetch = ['name', 'class', 'rollNumber'];

     fieldsToFetch.splice(2,1);//now array  having two elements ['name', 'class']

then

.only(...fieldsToFetch)

edited Mar 15, 2017 at 6:35

answered Mar 15, 2017 at 6:29

Hikmat Sijapati

6,9691 gold badge11 silver badges19 bronze badges

Collectives™ on Stack Overflow

How to convert JavaScript Array to elements

2 Answers 2

8 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

8 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related