javascript - Get the length of properties in a multidimensional array based on dimension? -

using vanilla javascript, want access length of multidimensional array based on "dimension" in.

example:

here's multidimensional array

  var myarray = [a, b, c, d, [e, [f], g]] 

dimension 0 in has 5 elements [a, b, c, d, [e, [f], g]]

dimension 1 has 3 elements [e, [f], g]

dimension 2 has 1 element [f]

this have far (which isn't lot go off of - i'm stuck)

var getlength = function(arr, dimension) {   subarray = [];   (var e in arr) {     if (e instanceof array) {        return e.length     }   } }  // getlength(myarray, 2) should equal 1 

can kindly help?

you reduce , recurse while keeping track of arrays have been seen:

var depthcount = function(xss, depth) {   depth = depth || 0   var seen = []   return xss.reduce(function(acc, xs) {     if (array.isarray(xs)) {       return acc.concat(depthcount(xs, depth + 1))     }     if (seen.indexof(xss) < 0) {       seen.push(xss)       return acc.concat({depth: depth, count: xss.length})     }     return acc   }, []) }  var xs = [1, 2, 3, 4, [5, [6], 7]]  console.log(depthcount(xs)) // [{depth: 0, count: 5}, //  {depth: 1, count: 3}, //  {depth: 2, count: 1}] 

then can find out total filtering collection depth , checking count. if sum counts work when have multiple arrays of same depth too:

var xs = [1, [2, 3], [4, 5, [6, 7]]]  var count = depthcount(xs)  console.log(count) // [{depth: 0, count: 3}, //  {depth: 1, count: 2}, //  {depth: 1, count: 3}, //  {depth: 2, count: 2}]  var counttotaldepth = function(depth, coll) {   return coll.filter(function(obj) {     return obj.depth === depth   }).reduce(function(x, y) {     return x.count + y.count   }) }  console.log(counttotaldepth(1, count)) // 5