Convert array of arrays to string?

Question

Given an array of arrays with 2 vals such :

var arrayStd = [["G14",18],["G16",17],["G16",17],["G13",17]];

I currently use this or variations of this :

var arrayStd = [["G14",18],["G16",17],["G16",17],["G13",17]];

var arrayToString = function(array){ 
  var str;
  array.map(function(a) {
    var item = a[0]+":"+a[1];
    str = str? str+'; '+item : item;
    } 
  );
return str
}
var str = arrayToString(arrayStd);
console.log(JSON.stringify(str));

Or

var arrayStd = [["G14",18],["G16",17],["G16",17],["G13",17]];

var arrayToString = function(array){ 
  return str =  JSON.stringify(array).replace(/\"|\[\[|\]\]/g , "").replace(/\],\[/g , "; ").replace(/,/g , ":");
}
var str = arrayToString(arrayStd);
console.log(JSON.stringify(str));

Is there a slicker way to do obtain str= "G14:18; G16:17; G16:17; G13:17"

really no reason to use stringify, join("; ") will do it [["G14",18],["G16",17],["G16",17],["G13",17]].map(i=>i.join(':')).join('; ') — epascarello
– epascarello, Commented May 4, 2018 at 12:36
I'm voting to close this question as off-topic because it seems like a better fit for codereview.stackexchange.com — epascarello
– epascarello, Commented May 4, 2018 at 12:36
Seems return str = array.join("; ").replace(/,/g,":") would do :D — Hugo LOPEZ
– Hugo LOPEZ, Commented May 4, 2018 at 12:38

Mohammad Usman · Accepted Answer · 2018-05-04 12:37:33Z

4

You can use .map() and .join() like this:

let str = arrayStd.map(a => a.join(":")).join("; ");

Demo:

let arrayStd = [["G14", 18], ["G16", 17], ["G16", 17], ["G13", 17]];

let str = arrayStd.map(a => a.join(":")).join("; ");

console.log(str);

answered May 4, 2018 at 12:37

Mohammad Usman

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1 Comment

Hugo LOPEZ Over a year ago

Oh I see ! You enter deeper so you use map().join().join() and not join().replace() ! :D

user2437417 · Accepted Answer · 2018-05-04 12:41:55Z

Making incremental improvements to your code...

You should be using .forEach() instead of .map() since you're not returning anything.

var arrayStd = [
  ["G14", 18],
  ["G16", 17],
  ["G16", 17],
  ["G13", 17]
];

var arrayToString = function(array) {
  var str = "";
  array.forEach(function(a) {
    var item = a[0] + ":" + a[1];
    str = str ? str + '; ' + item : item;
  });
  return str
}
var str = arrayToString(arrayStd);
console.log(JSON.stringify(str));

However, .map() is actually useful here to map each inner array to a string, then take the new array of strings and join them.

var arrayStd = [
  ["G14", 18],
  ["G16", 17],
  ["G16", 17],
  ["G13", 17]
];

var arrayToString = function(array) {
  var str = array.map(function(a) {
    return a[0] + ":" + a[1];
  }).join("; ");

  return str
}
var str = arrayToString(arrayStd);
console.log(JSON.stringify(str));

You can also use .join() on the inner array, and can get rid of the str variable by returning the result immediately.

var arrayStd = [
  ["G14", 18],
  ["G16", 17],
  ["G16", 17],
  ["G13", 17]
];

var arrayToString = function(array) {
  return array.map(function(a) {
    return a.join(":");
  }).join("; ");
}
var str = arrayToString(arrayStd);
console.log(JSON.stringify(str));

Finally, in modern environments, you can convert your functions to "arrow functions" to get a more concise syntax.

const arrayStd = [
  ["G14", 18],
  ["G16", 17],
  ["G16", 17],
  ["G13", 17]
];

const arrayToString = array => array.map(a => a.join(":")).join("; ")

var str = arrayToString(arrayStd);
console.log(JSON.stringify(str));

I also changed var to const, which is a good idea for variables you won't modify.

Hugo LOPEZ · Accepted Answer · 2018-05-04 13:10:56Z

1

Highly inspired by previous suggestions, yet shorter and more readable than others :

var arrayStd = [["G14",18],["G16",17],["G16",17],["G13",17]];

var arrayToString = function(array){ 
  return array.join("; ").replace(/,/g,":")
}
console.log(arrayToString(arrayStd));

edited May 4, 2018 at 13:10

answered May 4, 2018 at 12:50

Hugo LOPEZ

6451 gold badge8 silver badges21 bronze badges

1 Comment

user2437417 Over a year ago

People generally won't do this because it's performing all the same joins, but then needs to go back and create a whole new strings after a search and replace. Does work though, as along as you can guarantee that there will be no commas in the provided text.

Renzo Calla · Accepted Answer · 2018-05-04 12:43:25Z

0

You can use map function, and join the resulting array.

let arrayStd = [["G14",18],["G16",17],["G16",17],["G13",17]];
//"G14:18; G16:17; G16:17; G13:17"

let arrayNew = arrayStd.map((elem,i) => `${i!==0?'; ':''}${elem[0]}:${elem[1]}`).join("");
console.log(arrayNew);

edited May 4, 2018 at 12:43

answered May 4, 2018 at 12:37

Renzo Calla

7,7362 gold badges25 silver badges39 bronze badges

Comments

Yogy Saini · Accepted Answer · 2018-05-04 12:48:38Z

0

let arrayStd = [["G14",18],["G16",17],["G16",17],["G13",17]];
//"G14:18; G16:17; G16:17; G13:17"

let arrayNew = arrayStd.map((elem,i) => `${i!==0?'; 
':''}${elem[0]}:${elem[1]}`).join("");
console.log(arrayNew);

answered May 4, 2018 at 12:48

Yogy Saini

324 bronze badges

2 Comments

Hugo LOPEZ Over a year ago

Short but opaque.

user2437417 Over a year ago

The code is invalid. And this kind of template literal usage is very difficult to decipher.

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