Edit in JSFiddle

var countries = 'US,Germany,UK,Japan,Italy,Greece'.split(',');
var data = [];
for (var i = 0; i < countries.length; i++) {
    data.push({
        id: i,
        country: countries[i % countries.length],
        date: new Date(Date.now() - (Math.random() * 1000000000)),
        amount: Math.random() * 10000,
        active: i % 4 === 0
    });
}

var grid = new wijmo.grid.FlexGrid('#FlexGrid');
grid.itemsSource = data;
grid.columns[3].width = 100;

grid.itemFormatter = function (panel, r, c, cell) {
    if (panel.cellType == wijmo.grid.CellType.ColumnHeader) {
        if (panel.columns[c].binding ==  'country') {
            cell.innerHTML = "<span class='fa fa-globe'></span> " + cell.innerHTML;
        }
        else if (panel.columns[c].binding ==  'date') {
            cell.innerHTML = "<span class='fa fa-calendar'></span> " + cell.innerHTML;
        }
        else if (panel.columns[c].binding ==  'amount') {
            cell.innerHTML = "<span class='fa fa-balance-scale'></span> " + cell.innerHTML;
        }
        else if (panel.columns[c].binding ==  'active') {
            cell.innerHTML = "<span class='fa fa-check-square-o'></span> " + cell.innerHTML;
        }
    }
}
<div id="FlexGrid"></div>