Turns out you shouldn't use == in javascript, JS doesn't have warnings/strict (although it will have strict in the future)

'' == '0'          // false
0 == ''            // true
0 == '0'           // true
false == 'false'   // false
false == '0'       // true
false == undefined // false
false == null      // false
null == undefined  // true
" \t\r\n " == 0    // true
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