var el1 = document.getElementById("block1").test1;
var el2 = document.getElementById("block1").test2;This rule aims to reduce DOM access assigning its object to variable when access multiple time. It saves CPU cycles.
Examples of incorrect code for this rule:
var el1 = document.getElementById("block1").test1;
var el2 = document.getElementById("block1").test2;Examples of correct code for this rule:
var blockElement = document.getElementById("block1");
var el1 = blockElement.test1;
var el2 = blockElement.test2;