currently i use mammoth package . in that math function not converted in html so i refer your omml2mathml package in that i passed {http://schemas.openxmlformats.org/officeDocument/2006/math}oMath this element to omml2mathml() function but it return null . where actual problem.
if (element.name == "{http://schemas.openxmlformats.org/officeDocument/2006/math}oMath")
element = MathXml(element);
i call my own function when math element ignore by mammoth package
function matchXml(element)
{
var omml2mathml = require('omml2mathml');
var mathmlElement = omml2mathml(element);
}