In fact, you don’t need to store each column as a Key. You can make the data of these three columns into a JS object, and then store the stringified value in localStorage, for example:

var col_identifier = {
    col1: ...
    col2: ...
    col3: ...
};

localStorage.setItem('col_identifier', JSON.stringify(col_identifier));

When using it, directly take out this value, then analyze it, and then take out the values ​​​​of col1, col2 and col3 for comparison

var col_identifier = JSON.parse(localStorage.getItem('col_identifier') || '{}');

var col1 = col_identifier.col1 || '';
var col2 = col_identifier.col2 || '';
var col3 = col_identifier.col3 || '';

... // 下面就是对比表格数据了

Can I pin multiple lines? If yes, you can save an array.

I feel that comparing 3 attributes is too complicated. You can give each row a unique id, so you only need to see if the id matches.