As stated in the comments, this would be more efficiently achieved if the text file was encoded in JSON. However without knowing how the text file is being produced I can't recommend a method to generate it as JSON, so here's how you might parse your current file.
Assuming you're are reading the content of the text file in the frontend, you would asynchronously get the content of the text file using XMLHttpRequest. Once you've received the file content you would turn it into an array. In the specific case that you've provided where the text file is of the form [Skin1],[skin2],[skin3], you would remove the first [ and last ], and then split by the delineation ],[.
function httpGet(url, callback) {
// this function gets the contents of the URL. Once the
// content is present it runs the callback function.
var xmlhttp=new XMLHttpRequest();
xmlhttp.onreadystatechange=function() {
if (xmlhttp.readyState==4 && xmlhttp.status==200) {
callback(xmlhttp.responseText);
}
}
xmlhttp.open("GET", url, false );
xmlhttp.send();
}
httpGet("url-of-your-file", function(textFile){
// this calls the httpGet function with the URL of your text
// file. It then runs a function that turns the file into an
// array.
var array = textFile.slice(1, -1).split("],[");
console.log(array);
});
JSON.parseto turn its text into an array immediately.