Generate new property names without collision in an object

Question

How can I Create a Variable based on other variables' names? For example if i have a variable named 'a' then i want to create a new variable and name it 'a2'. And if the variable a2 exists then I want to create another one called 'a3' etc... how can I achieve this with javascript?

Are you using [modules](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules) or global context (regular javascript tags)? — Mosh Feu, Jun 07 '20 at 11:13
What are you trying to accomplish? It sounds like you want to use an array or list rather than actual variables? Can you give an example of what you are trying to accomplish? — Patrick, Jun 07 '20 at 11:14
This should help you https://stackoverflow.com/questions/5117127/use-dynamic-variable-names-in-javascript — vrachlin, Jun 07 '20 at 11:14
See this: https://stackoverflow.com/questions/5117127/use-dynamic-variable-names-in-javascript. — Saurabh Agrawal, Jun 07 '20 at 11:18
You never need or want dynamic variable names. Please use an object instead, or an array, e.g. `const a = [3, 4, 5]; console.log(a[1], a[2]); a.push(6); console.log(a[3]);`. See [Use dynamic variable names in JavaScript](https://stackoverflow.com/questions/5117127/use-dynamic-variable-names-in-javascript). — Sebastian Simon, Jun 07 '20 at 11:18
The answers in question https://stackoverflow.com/questions/5117127/use-dynamic-variable-names-in-javascript just name the variables based on their contents what I wanted was to name variables based on the NAME of the other variables — Mohamed Technology, Jun 07 '20 at 11:43

score 0 · Accepted Answer · answered Jun 07 '20 at 11:23

You want an array. Use an array. However, that being said, here's a disgusting hack to generate new properties.

function incrementName(old_name) {
  // check for number at end of name
  const number_match = old_name.match(/\d$/);
  if (number_match) {
    // increment number at end
    const next_num = ''+(Number.parseInt(number_match[0])+1);
    return old_name.substr(0,number_match.index) + next_num;
  }
  else {
    // otherwise just add a 2
    return old_name+'2';
  }
}

function getUnusedName(object,original_name) {
  let name = original_name;
  while (name in object) {
    name = incrementName(name);
  }
  return name;
}

// usage
const my_object = {
  'a':'boo',
  'b2':'bar'
}
my_object[getUnusedName(my_object,'a')] = 'foo';
my_object[getUnusedName(my_object,'b2')] = 'baz';
console.log(my_object);

Thanks For Your answer This seems To be What i Was looking For — Mohamed Technology, Jun 07 '20 at 11:52

Generate new property names without collision in an object

1 Answers1