CODEWITHSUNDEEP
javascriptarraysjavascript-objectsjscriptecmascript-3
AlexLaforge
AlexLaforge

Reputation: 532

How to convert a string into an Array of JScript Objects

In Javascript, I have a string that I need to convert to an Array of objects.

//ORIGINAL STRING :
var originalString = "[13, "2017-05-22 17:02:56", "Text111"], [25, "2017-05-22 17:03:03", "Text222"], [89, "2017-05-22 17:03:14","Text333"]";

I need to be able to loop through each object, and get the 3 properties by using indexes. That would give (for the first Array) :

myItem[0] => 13
myItem[1] => "2017-05-22 17:02:56"
myItem[2] => "Text111"

That first sounded simple to my head (and probably is), but after several attempts, I am still stuck.

Please note that I cannot use jQuery because running with a very old Javascript specification : "Microsoft JScript", which is EcmaScript 3 compliant.

I thank you ;)

Upvotes: 1

Views: 415

Answers (2)

Trash Can
Trash Can

Reputation: 6814

Something like this should do

var regex = /\[([^\]]+)/g;
var originalString = '[13, "2017-05-22 17:02:56", "Text111"], [25, "2017-05-22 17:03:03", "Text222"], [89, "2017-05-22 17:03:14","Text333"]';
var result = regex.exec(originalString);
var container = [];
for (var j = 0; result ? true : false; j++) {
  var tokens= result[1].split(',');
  var tempContainer = []
  for (var i = 0; i < tokens.length; i++) {
    tempContainer[i] = tokens[i].replace(/["\s]/g, '');
  }
  container[j] = tempContainer;
  // continue the search
  result = regex.exec(originalString);
}
console.log(container);

Upvotes: 1

Yeldar Kurmangaliyev
Yeldar Kurmangaliyev

Reputation: 34189

If you just could use JSON.parse, then you would be able to append [ and ] to the beginning and ending of a string respectively, and then parse it as an array of arrays. 

var originalString = '[13, "2017-05-22 17:02:56", "Text111"], [25, "2017-05-22 17:03:03", "Text222"], [89, "2017-05-22 17:03:14","Text333"]';

var result = JSON.parse("[" + originalString + "]");
console.log(result);

However, as far as I know, JSON.parse is not ECMAScript 3 complaint, so you will have to parse it yourself.
Something like this should help:

var originalString = '[13, "2017-05-22 17:02:56", "Text111"], [25, "2017-05-22 17:03:03", "Text222"], [89, "2017-05-22 17:03:14","Text333"]';

function trimString(str, trims) {
  var left = 0;
  var right = str.length - 1;
  
  while (left < right && trims.indexOf(str[left]) != -1) {
    left++;
  }
   
  while (left < right && trims.indexOf(str[right]) != -1) { 
    right--;
  }
  
  return str.substr(left, right - left + 1);
}

function splitByCommasOutOfBrackets(str) {
  var result = [];
  var current = "";
  var bracketBalance = 0;
  
  for (var i = 0; i < str.length; i++)
  {
    switch (str[i]) {
      case '[':
        current = current + str[i];
        bracketBalance++;
        break;
        
      case ']':
        current = current + str[i];
        bracketBalance--;
        break; 
        
      case ',':
        if (bracketBalance === 0) {
          result.push(trimString(current, [" ", "[", "]", "\""]));
          current = "";
        } else {
          current = current + str[i];
        }
        break;  
        
      default:
        current = current + str[i];
        break;
    }
  }
  
  if (current.length > 0) {
    result.push(trimString(current, [" ", "[", "]", "\""]));
  }
  
  return result;
}

var arr = splitByCommasOutOfBrackets(originalString);
console.log("1: Split by commas which separate arrays");
console.log(arr);

for (var i = 0; i < arr.length; i++) {
  arr[i] = splitByCommasOutOfBrackets(arr[i]);
}

console.log("2: Split every array by the same rules");
console.log(arr);

I am not quite sure what functionality exists in ECMAScript 3 and I used MDN for this. It looks like many functions even like String.prototype.trim do not exist in ECMAScript 3. So I had to reimplement it myself. If I am wrong and you can use them in JScript, then just use some of these functions instead.

The general idea of algorithm is the following:

  1. Split string by commas out of brackets, i.e. commas which separate our arrays. And then trim each string whitespaces, brackets, quotes - all these things that we don't need. As the result, we have an array of strings, each of them represents an array.
  2. Then apply the same rule for every array, separating it to values.

Note that all values are threaded as strings in this solution.

It could be rewritten in a recursive way instead of looping if you have more nested levels, but it would be less understandable - I just have provided a minimal solution which works :) I am sure you can improve it in many ways.

Upvotes: 1

Related Questions