@Anup I think you can try something along the lines of:
search.create({
    type: 'salesorder',
    filters: [
        ['isinactive', 'is', 'F'],
        'AND',
		['mainline', 'is', 'T']
    ],
    columns: [{
        name: "custbody_currentuser_hid",
        summary: s.Summary.COUNT
    }]
}).run().each(resultSet);