Android Question Javascript in webview issue

function ColoraSolo(elemento,colore) {
   var a = document.getElementById("svgObject");
   var svgDoc = a.contentDocument;   
   var baz = getElementsByAttribute(svgDoc,"clrto","xxy1");
   for (i = 0; i < baz.length; i++) {
     var att = document.createAttribute("opacity");
     att.value = 0;
     baz[i].setAttributeNode(att);
   }
   var svgItem = svgDoc.getElementById(elemento);
var child = svgItem.children;
var att = document.createAttribute("opacity");
att.value = 0.4;
var attw = document.createAttribute("fill");
attw.value = colore;
var ricn = document.createAttribute("clrto");
ricn.value = "xxy1";
for (i = 0; i < child.length; i++) {           //<<<------ Line 35
   child[i].setAttributeNode(att);   
   child[i].setAttributeNode(attw);
   child[i].setAttributeNode(ricn);   
}
}

Uncaught TypeError: Cannot read property 'length' of undefined in file:/// (Line: 35)