html - javascript array restart counting -

i have piece of code:

  //var data.name declared somewhere else, e.g. "sherlock". changes  often.   recents[recents.length] = data.name;   idthis = "recent" + recents.length;   if(recents.length >= 7) {   recents[0]=recents[7];   recents[1]=recents[8];   recents[2]=recents[9];   recents[3]=recents[10];   recents[4]=recents[11];   recents[5]=recents[12];   recents[6]=recents[13];   recents[7]=recents[14];   recents[0]=recents[15];   recents[1]=recents[16];   recents[2]=recents[17];   //etc   idthis = "recent" + (recents.length -7); } document.getelementbyid(idthis).innerhtml = data.name; 

my question how automate recents[0]=recents[7] recents[1]=recents[8] etc? point recent id can't higher 6, otherwise rest of code won't work.

it sounds me want slice original array. i'm not sure slice want, here's how first 8 items , last 8 items, maybe 1 of want:

// first 8 items recents. var first8 = recents.slice(0, 8); // last 8 items recents. var last8 = recents.slice(-8); // first8 , last8 contain 8 items each. 

of course, if recents array doesn't have 8 items, results slice less 8 items.

if want delete range in recents array, can use splice:

// delete first 8 items of recents. recents.splice(0, 8); // recents[0] value of former recents[8] (and on) 

you can use return value of splice items deleted:

// delete , first 8 items of recents. var deleteditems = recents.splice(0, 8); // add them end, example: recents = recents.concat(deleteditems);