问如何在javascript中找到嵌套数组的最大值/最小值？

EN

var columns = ["ColumnA", "ColumnB", "ColumnC"];

var max = selectedMax(columns,dataset);
var min = selectedMin(columns,dataset)

function selectedMax(columns, dataset) {
    var max;
    columns.forEach(function(element, index, array) {
        var tmpmax = d3.max(dataset, function(d) {
            return +d[element];
        });       
        max = (tmpmax > max || max === undefined) ? tmpmax : max;
    });
    return max;
}

function selectedMin(columns, dataset) {
    var min;
    columns.forEach(function(element, index, array) {
        var tmpmin = d3.min(dataset, function(d) {
            return +d[element];
        });
        min = (tmpmin < min || min === undefined) ? tmpmin : min;
    });  
return min;
}