How do i save a string and then use is as a variable name?

Question

I am trying to save a string variable and then use this variable as an other variable.

I am saving a string in the "name" variable that can be "weekly", "monthly" or "quarterly".

and then use is as a "this.weekly" but using the "name" reference. Just for not going through the "swtich" for each case.

This is my code:

    // Update "report" variable onclick checkbox
    checkboxSaveOnChange: function(newCheckbox){

        var name = newCheckbox.checked;


        if (newCheckbox.checked) {
            this.name.push(newCheckbox.value);  
        } else {
            var index = this.name.indexOf('newCheckbox.value'); 
            this.name.splice(index, 1); 
        }

        /*switch (name) {

            case 'weekly': 


            break;

            case 'monthly': 

            break; 

            case 'quarterly': 

            break;

        }*/


        console.log(this.weekly);
        console.log(this.monthly);
        console.log(this.quarterly);
    },

tried using var name = 'this.+'newCheckbox.checked; - doesn't work...

EDIT:

This is still resulting the error:

    // (newCheckbox.checked) ? this.name.push(newCheckbox.value) : this.name.indexOf('newCheckbox.value');
    if (newCheckbox.checked) {
        this[name].push(newCheckbox.value);     
    } else {
        var index = this[name].indexOf('newCheckbox.value'); 
        this[name].splice(index, 1);    
    }

Can you submit an example? I changed `var index = this[name].indexOf('newCheckbox.value');` and `this[name].splice(index, 1);` and still get the error `TypeError: this.name is undefined` — Imnotapotato, Jan 18 '18 at 14:54
Are you still console logging `this.name`? or haven't changed `this[name].push`? — Albzi, Jan 18 '18 at 14:54
Note that the value of the `checked` attribute of a DOM checkbox element will always be either boolean `true` or `false`, so your `name` variable will be one of those. Until you've initialized `this[name]` it will be `undefined`, so your code will fail for that reason. — Pointy, Jan 18 '18 at 14:57
yes, edited my post at the bottom with the current code lines — Imnotapotato, Jan 18 '18 at 14:57
@Pointy this was my problem! `name = newCheckbox.checked` should be `name = newCheckbox.name`... working for toooo many hours :( — Imnotapotato, Jan 18 '18 at 15:01

smtaha512 · Answer 1 · 2018-08-16T15:49:30.210

3

Try using this[name]. In JavaScript property accessors can work with dot notation as well as bracket notation. You can see the docs from Mozilla Developer Network MDN for details.

edited Aug 16 '18 at 15:49

answered Jan 18 '18 at 14:54

smtaha512

420
5
11

score 1 · Accepted Answer · answered Jan 18 '18 at 15:07

Here's an example to elaborate on the previous answer.

var thingy = {
  weekly: false,
  monthly: false,
  quarterly: false,
  checkboxSaveOnChange: function(newCheckbox) {
    var value = newCheckbox.value,
        checked = newCheckbox.checked;
    this[value] = checked;
  }
};

document.getElementsByTagName("button")[0].onclick = function(){
  var cbs = document.querySelectorAll("input[type='checkbox']");
  for(var i=0; i<cbs.length; i++) thingy.checkboxSaveOnChange(cbs[i]);
  console.log(thingy);
};

<label><input type=checkbox value=weekly />weekly</label>
<label><input type=checkbox value=monthly />monthly</label>
<label><input type=checkbox value=quarterly />quarterly</label>
<button>do a thing</button>

How do i save a string and then use is as a variable name?

2 Answers2