gistfile1.js

function SymbolContainer(theSymbol){
    this.child = null; // reference to single child container
    this.symbolItems = null; //array of symbols
    this.parent = null;
}

SymbolContainer.prototype.checkIfChild = function(containerToCheckIfChild) {
    this.parent = [];
    var childVB = containerToCheckIfChild.visibleBounds,
        childLeft = childVB[0],
        childTop = Math.abs(childVB[1]),
        childRight = childVB[2],
        childBottom = Math.abs(childVB[3]);
    var parentVB = this.parent.visibleBounds,
        parentLeft = parentVB[0],
        parentTop = Math.abs(parentVB[1]),
        parentRight = parentVB[2],
        parentBottom = Math.abs(parentVB[3]);
        
    if(childLeft >= parentLeft && childTop >= parentTop && childRight <= parentRight && childBottom <= parentBottom){
        this.parent = containerToCheckIfSmaller;
     }
}

var containerToCheckIfChild = doc.pageItems[0];

var mySymbolContainer = new SymbolContainer();
mySymbolContainer.checkIfChild(containerToCheckIfChild);

$.writeln(mySymbolContainer.parent);