I have trouble finding a solution for ID in one of the 2 syntaxes either input or select in html to load it in the identifier Id of the "DIV", called "content" following the "if (nblig == 0)

for my simple test, I put the 2 inputs with ID = "rsl2" with the "if (nblig == 0) and "var nblect_Serv = 2;" to see. it doesn't work

if I put the single quotes: ID = 'rsl2', error message: userCodeAppPanel: 27

Uncaught SyntaxError: Unexpected identifier

if I put the double quotes: ID: "rsl2", error message: userCodeAppPanel: 19

Uncaught TypeError: Cannot set properties of null (setting 'value')

if I remove the IDs from the input and replace: "content = ' ZERO ';" and "content = ' sup ZERO ';", it works!

So how to fix the problem on input ID?

Here is my small sample below: line n ° 1807 and 1813