Insert a string at a specific index

Question

How can I insert a string at a specific index of another string?

 var txt1 = \"foo baz\"

Suppose I want to insert \"bar \" after the \"foo

Answer 1

my_string          = "hello world";
my_insert          = " dear";
my_insert_location = 5;

my_string = my_string.split('');  
my_string.splice( my_insert_location , 0, my_insert );
my_string = my_string.join('');

https://jsfiddle.net/gaby_de_wilde/wz69nw9k/