Identify word square in O(n)

wordsquare.js

var line = "BALL AREA LEAD LADY";
var wordAry = line.split(" ");
console.log(wordAry);

var rowIdx = 0;
var colIdx = wordAry.length;
var len = colIdx;
var isWordSquare = true;

while(colIdx > 0 && rowIdx < len){
	if(wordAry[rowIdx][len - colIdx] != wordAry[len-colIdx][rowIdx]){
		console.log("Not a word square");
		isWordSquare = false;
		break;
	} else {
		--colIdx;
	}
	if(len - colIdx == len){
		++rowIdx;
		colIdx = len;
	}
}
if(isWordSquare){ console.log("word square is it."); }