Build object tree on array of strings with hierarchy of roles and getting of leaves from this tree.

ObjectsTree.js

    var data = [
    	'all', 'all/staff', 'all/staff/developer', 'all/staff/manager', 'all/staff/engineer', 
    	'all', 'all/other', 'all/other/writer', 'all/other/hr'
    ];
    
    var delimeter = '/';
    	
    function getStructure(data) {
      var structure = {
        isLeave: true
      };
      data.forEach(function(s) {
      	builder(structure, s.split(delimeter));
      })
      return structure;
    }
    
    function builder(struct, item) {
    	if (!item.length) return;
    	
      var name = item.splice(0, 1);
    	if (!struct[name]) {
    	  struct.isLeave = false;
        struct[name] = {
          isLeave: true
        };
      }
      
      builder(struct[name], item);
    }
    
    
    function getLeaves(struct, name, leaves) {
      if (struct.isLeave) {
        leaves.push(name);
        return;
      }  
      
      for (p in struct) {
        if (p == 'isLeave') {
          continue;
        }
        getLeaves(struct[p], (name ? name + delimeter + p : p), leaves);
      }
    }
    

    var leaves = [];
    getLeaves(getStructure(data), '', leaves)
    console.log(leaves);