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simply copy/paste the lib.js file's code into your js file and you are done!
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To use this, do this in your main file or the file you want to use these functions in:
const alertSys = require("./lib.js");
let test = "Hello";
if (test !== "Hello") {
alertSys.error("invalid string!");
altertSys.warn("invalid string!");
alertSys.alert("invalid string!");
}