first unique character in a string code example

Example 1: python3 return a list of indexes of a specific character in a string

string='mississippi'
s='s'
lst= []
for i in range(len(string)):
    if (string[i] == s):
        lst.append(i)
print(lst)
#result: [2, 3, 5, 6]

Example 2: replace all character in string javascript

let a = "How to search and replace a char in a string";
while (a.search(" ", ""))
{
   a = a.replace(" ", "");
}
console.log(a);