javascript - Access an array item in its definition, relative index -

i trying define array:

    postlists = [     [         [46276,76235,78128],         postlists[0][0].length,         1100     ], [         [],         postlists[1][0].length,         0     ] ]; 

however, undefined error postlists[x][0].length lines.

how access array being defined itself? there way relatively select item without referencing entire "path" folders? example in case, [0].length [46276,76235,78128]'s length, or ..[1] (parent) select postlists[1].

postlists[x][0] hold hundreds of thousands of integers, performance need considered.
postlists[x][1] original length needs accessed every few seconds, because of size of postlists[x][0], cannot accessed on fly without harming performance.
postlists[x][2] index keep track (and store) items processed, in postlists[0][2] 1100 used skip 1100 first items have been processed.

i using in greasemonkey script, reason sub-arrays in postlists plan use script on multiple tabs running @ same time.

the start of script setup this:

window.onkeydown = function(event) {     if (event.ctrlkey && event.altkey) {         switch(event.keycode) {             case 49: activelist = postlists[0]; break; // 1             case 50: activelist = postlists[1]; break; // 2             case 51: activelist = postlists[2]; break; // 3             case 52: activelist = postlists[3]; break; // 4              case 70: // f                 togglescript = !togglescript;                 if (togglescript) {                     treatitem();                     favobserver.observe(topnotice, {attributes: false, childlist: true, characterdata: true});                 } else                     stopobserving(true);                 break;         }     } }; 

every functions use activelist refer selected sub-array.

you can utilize assignment, side-effect of creating additional variable; e.g., tmp, used assign, re-assign variable can change multiple occassions

var tmp, postlists = [    [      tmp = [46276, 76235, 78128],      tmp.length,      1100    ],    [      tmp = [],      tmp.length,      0    ]  ];  delete tmp;  console.log(postlists);