Dynamically changing a method name in JavaScript

You can use bracket notation in objects, to use variables like this:

headerCaptions.push(localization['SCREEN_EPISODE_INITIATION_HEADER_REQUEST'+i]);

Then you can use a loop:

for(var i = 0; i < 3; i++) {
    headerCaptions.push(localization['SCREEN_EPISODE_INITIATION_HEADER_REQUEST'+i]);
}

Using ES6 syntax, you could call something like this:

const n = 4;
for (let i = 0; i < n; i++) {
  headerCaptions.push(localization[`SCREEN_EPISODE_INITIATION_HEADER_REQUEST${i}`])
}

Since JavaScript object attributes can be accessed either by calling object.property or object['property'], we can programatically access the attributes of location that are of interest by manipulating a string.

The `` syntax uses string interpolation, allowing you to insert computed values / variables into a string by surrounding it by ${}

In JavaScript, you can access object properties using either the dot syntax (which you have used in your example) or the substring syntax, which looks like this:

headerCaptions.push(localization["SCREEN_EPISODE_INITIATION_HEADER_REQUEST1"]);

Since the square brackets just contain a string, it's possible to dynamically generate them.

headerCaptions.push(localization["SCREEN_EPISODE_INITIATION_HEADER_REQUEST" + i]);

Now all you need to do is loop through your numbers.

var i = 1;
var il = 4;
while (i < il) {

    headerCaptions.push(localization["SCREEN_EPISODE_INITIATION_HEADER_REQUEST" + i]);
    i += 1;

}

for(var i=0; i<5; i++){

    if(!localization.hasOwnProperty("SCREEN_EPISODE_INITIATION_HEADER_REQUEST"+i))
       break;

    headerCaptions.push(localization["SCREEN_EPISODE_INITIATION_HEADER_REQUEST"+i);

}

The syntax a.b is equivalent to a['b'], so you can just do

for(var i = 1; i <= n; i++) {
  headerCaptions.push(localization['SCREEN_EPISODE_INITIATION_HEADER_REQUEST' + i]);
}

However, it might be better to just store these values in an array.