reference a number field/title in JSON array

I am searching a json array full of google fonts. The fonts are organized by family -> files – >filename. The issue I am having is that the filename is sometimes stored as a number. For example (see bottom of array under "files" titled "100"):

"family": "Roboto",
      "variants": [
        "100",
        "100italic",
        "300",
        "300italic",
        "regular",
        "italic",
        "500",
        "500italic",
        "700",
        "700italic",
        "900",
        "900italic"
      ],
      "subsets": [
        "cyrillic",
        "cyrillic-ext",
        "greek",
        "greek-ext",
        "latin",
        "latin-ext",
        "vietnamese"
      ],
      "version": "v30",
      "lastModified": "2022-09-22",
      "files": {
        "100": "http://fonts.gstatic.com/s/roboto/v30/KFOkCnqEu92Fr1MmgWxPKTM1K9nz.ttf",
"regular": "http://fonts.gstatic.com/s/roboto/v30/KFOmCnqEu92Fr1Me5WZLCzYlKw.ttf"

I can call the font file "regular" while iterating the json array, but I am not sure how to refer to the file labelled as "100" since I know numbers cannot be variables.

$.getJSON('https://www.googleapis.com/webfonts/v1/webfonts?key=mykey',    function(response) {
            var items = response.items;
            items.forEach(function(fontitem){
              if (fontitem.family == "Roboto") {
                  alert(fontitem.files.$100); //doesn't work
                                  alert(fontitem.files.regular); //works
                  return;
                  }
              });
          });

alert(fontitem.files.$100); //doesn't work while
alert(fontitem.files.regular); //works

>Solution :

You can use the bracket notation – files['$100'], which accepts a string as the key parameter.