diff --git a/js/index.js b/js/index.js
index d3a72f3..a9b9d0f 100644
--- a/js/index.js
+++ b/js/index.js
@@ -199,4 +199,31 @@ x = Math.SQRT2; //sqrt(2)
 console.log(x);
 //--------------------------------------------------------------------------------------------------------------
 
-//https://youtu.be/8dWL3wF_OMw?t=2220
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+//12.Useful string methods
+let userName = "WickedJack99"
+console.log(userName.length); // get length of string
+console.log(userName.charAt(0)); // get charAt x of string starting index is 0
+console.log(userName.indexOf("c")); // get first occurence-index of letter x
+console.log(userName.lastIndexOf("c")); // get last occurence-index of letter x
+console.log(userName.trim()); // removes whitespaces
+console.log(userName.toUpperCase()); // changes whole string to upper case
+console.log(userName.toLowerCase()); // changes whole string to lower case
+let phoneNumber = "0123 335321";
+console.log(phoneNumber.replaceAll("3", "0")); // replaces all 3s of phoneNumber by 0
+//--------------------------------------------------------------------------------------------------------------
+
+//13.String-slicing
+//Extracts a section of a string and returns a new string without modifying the original string.
+let omName = "Wicked Jack99";
+let firstName2;
+let lastName2;
+//firstName2 = omName.slice(0,6);
+//lastName2 = omName.slice(7);
+firstName2 = omName.slice(0, omName.indexOf(" "));
+lastName2 = omName.slice(omName.indexOf(" ") + 1);
+console.log(firstName2);
+console.log(lastName2);
+//--------------------------------------------------------------------------------------------------------------
+
+//14.Method chaining
+//https://youtu.be/8dWL3wF_OMw?t=3554
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