Create a JS multidimensional array from string

Question

I would like to create a miltidimentional array as follows so

var multi-arr = [
 ["A,2,5"], 
 ["B,4,4"], 
 ["C,4,4"]
 ]

from string values gotten from the database using ajax.

string data gotten from db delimited by #

var string = "A,2,5# B,4,4# C,4,4";

I split the string by a '#' delimiter

arr1=string.split(/\s*\#\s*/g);

creating the array below

var arr = ["A,2,5", "B,4,4", "C,4,4"];

I want to further split the items in the above array using the comma ',' as a delimiter and create a multidimensional array

My problem is the loop only pushes in the last item in the array

for (i = 0; i < arr.length; i++) { 
 var arr2 = [];
 arr2[i]=arr2.push(arr1[i].split(/\s*,円\s*/g));
 }
console.log(arr2);

What am i doing wrong? or what can i do better?

• Mike 'Pomax' Kamermans: why not rewrite it to JSON and just parse that?

Answer 1

You could split it, but you have all the delimiters in place anyway, just rewrite your string to be JSON-conformant and run it through JSON.parse():

// base string
var str = "A,2,5# B,4,4# C,4,4";
// quote text data. If the array was plain number data, we don't even need this step.
var quoted = str.replace(/([a-zA-Z]+)/g,'"1ドル"');
// rewrite to JSON form for a nested array
var jsonStr = "[[" + quoted.replace(/#/g,'],[') + "]]";
// done, just tell the JSON parser to do what it needs to do.
var arr = JSON.parse(jsonStr);

And that's it, arr is now the nested array [["A",2,5],["B",4,4],["C",4,4]].

Answer 2

This should work

var str = "A,2,5# B,4,4# C,4,4";
var arr = str.split(/\s*\#\s*/g);
 for (var i = 0; i < arr.length; i++) { 
 arr[i]=arr[i].split(/\s*,円\s*/g);
 }
console.log(arr)

In your solution var arr2 = []; needs to be outside the for loop, or it gets redefined everytime. However, we don't really need to define a separate var and simply update the original array.

Answer 3

The var statement should be outside the for loop and you don't need to do the assignment and the push.

var i;
var string = "A,2,5# B,4,4# C,4,4";
var arr1 = string.split("#");
var arr2 = [];
for (i = 0; i < arr1.length; i++) {
 arr2[i]=arr1[i].split(",");
} 
console.log(arr2);

As suggested by Mike 'Pomax' - you could return the data from the server as JSON. If you're using PHP, that can be done like so:

header('Content-Type: application/json');
echo json_encode($queryResult);
exit;

• Victor Njoroge: That's what i was doing wrong. But i'll use Mike 'Pomax' s method.
• Mike 'Pomax' Kamermans: just remember not to trust your server's response (becaue 404s, 500s, etc), and use a try/catch, because if you're feeding data to JSON.parse() without knowing for certain what's in it (like in my answer), it can throw and cause your script to error out.
• user2182349: For fun - you can compare the performance of these solutions: jsperf.com/string-to-multi-array. Performance will likely vary on different data sets, one one of these solutions has an additional check on the content of the array.

Answer 4

Here is a simple solution that should work on modern browsers:

var string = "A,2,5# B,4,4# C,4,4";
var multiArray = string.split(/\s*\#\s*/g).map(function(substr) {
 return [substr];
});

Answer 5

You just need to loop over each element in the array again after your first split. I would use Array.prototype.map as it will return you a new array without mutating the original.

I also did a check to see if the value in the inner array was a number. if it was it is parsed to an actual number.

var arr = ["A,2,5", "B,4,4", "C,4,4"];
console.log(arr);
var multidimensional = arr.map(function(item) {
 // you need to split the elements in your array
 return item.split(/,/).map(function(val) {
 // you may as well check if it's a string or a Number
 return parseIfNumber(val);
 })
});
console.log(multidimensional);
// helper functioon
function parseIfNumber(val) {
 return /^[0-9.-]+$/.test(val) 
 ? Number(val) 
 : val;
}

<script src="http://codepen.io/synthet1c/pen/WrQapG.js"></script>

Answer 6

From your current arr variable - ["A,2,5", "B,4,4", "C,4,4"] - you can create your multi_arr variable like so:

var multi_arr = [];
arr.forEach(function(a) {
 multi_arr.push([a]);
});

Keep in mind, this will create the array exactly as the example of what you were looking for, which was this:

var multi-arr = [
 ["A,2,5"], 
 ["B,4,4"], 
 ["C,4,4"]
 ]

If you want each of the items in the inner arrays to be split as well, this will work for you:

var multi_arr = [];
arr.forEach(function(a) {
 multi_arr.push(a.split(','));
});