Making ESLint work for files which are loaded by others - eslint

Question

I have a set of scripts in which one loads another script file and uses the functions defined in it.
For example, let's say I have main.js script with the following source
load("helper.js");
var stdin = new java.io.BufferedReader( new java.io.InputStreamReader(java.lang.System['in']) );
function readline() {
var line = stdin.readLine();
return line;
}
var N = parseInt(readline());
for(var i = 0; i< N; i++)
{
print("fd630b881935b5d43180ff301525488a");
var num = parseInt(readline());
var ans = perfectNumberCheck(num);
print(ans);
print("dc29e6fa38016b00627b6e52956f3c64");
}
I have another script file, helper.js which has the following source
function perfectNumberCheck(num) {
if(num == 1)
{
return 0;
}
var halfNum = (num/2) + 1;
var sum = 0;
var retVal = 0;
for(var i=1 ; i < halfNum; i++){
if(num % i === 0){
sum = sum + i;
}
}
if(sum == num){
retVal = 1;
}
else {
retVal = 0;
}
return retVal;
}
As it can be seen, main.js uses the function perfectNumberCheck. Now, when I run ESLint on both the files using eslint main.js helper.js or by using eslint *.js, I get the no-unused-vars error 'perfectNumberCheck' is defined but never used even though it is being used in main.js.
I want to keep this error in the configuration but don't want ESLint to show it in such cases.
Is there a way to make ESLint resolve these dependencies without writing the entire code in a single script file?

Answer 1

You can add a comment like /* exported perfectNumberCheck */ to helper.js to tell no-unused-vars that the function is used elsewhere outside that file:
/* exported perfectNumberCheck */
function perfectNumberCheck() {
// ...
}
By itself, ESLint lints each file in isolation, so it will not resolve identifiers defined in other files. The /* exported ... */ comment and globals allow you to inform ESLint of dependencies in other files.
Since exported comments are intended to be used to indicate names that are used elsewhere by being present in the global scope, they have no effect when the file's source in not in the global scope. Specifically, quoting the docs:
Note that /* exported */ has no effect for any of the following:
when the environment is node or commonjs
when parserOptions.sourceType is module
when ecmaFeatures.globalReturn is true