var myChart = echarts.init(document.getElementById('root'));

option = {
    series: [{
        type: 'treemap',
        visualDimension: 1,
        colorMappingBy: 'value',
        color: function(params) {
            a = params.value;
            if (a >= 5) {
                return 'darkgreen';
            } else if (a >= 0 && a<5) {
                return 'green';
            } else if (a <= -5) {
                return 'darkred';
            } else {
                return 'red';
            }
        },
        data: [{
            name: 'nodeA',            // First tree
            value: [5, -10],
            children: [{
                name: 'nodeAa',       // First leaf of first tree
                value: [1, -2]
            }, {
                name: 'nodeAb',       // Second leaf of first tree
                value: [4, -18]
            }]
        }, {
            name: 'nodeB',            // Second tree
            value: [10, 20]
        }]
    }]
};
myChart.setOption(option);