javascript：将函数的输出更改为指定的小数位

Question

我的 javascript 不是很好，但最近需要使用库来输出聚合表。正在使用fin-hypergrid。

有一部分我需要在一个对象中插入一个求和函数（本例中为 rollups.sum(11)），以便它可以计算表中的聚合值，如下所示：

aggregates = {Value: rollups.sum(11)}

我想将此值更改为返回 2 位小数并尝试：

rollups.sum(11).toFixed(2)

但是，它给出了错误：“rollups.sum(...).toFixed is not a function”

如果我尝试类似：

parseFloat(rollups.sum(11)).toFixed(2)

它抛出错误：“无法分配给 (new String("NaN")) 的属性：不是对象”

所以它必须是一个函数对象。

我想知道是否有办法改变函数 rollups.sum(11) 以返回带 2 个小数位的函数对象？

(side info: rollups.sum(11) 来自一个模块：

sum: function(columnIndex) {
    return sum.bind(this, columnIndex);
}

)

抱歉，由于数据机密性问题，我无法在此处发布示例输出。 但是，这是我遵循的示例中的代码。我基本上需要更改 rollups.whatever 以给出小数位。这里sum(11)中的“11”指的是一个“列索引”。

window.onload = function() {

var Hypergrid = fin.Hypergrid;
var drillDown = Hypergrid.drillDown;
var TreeView = Hypergrid.TreeView;
var GroupView = Hypergrid.GroupView;
var AggView = Hypergrid.AggregationsView;

// List of properties to show as checkboxes in this demo's "dashboard"
var toggleProps = [{
        label: 'Grouping',
        ctrls: [
            { name: 'treeview', checked: false, setter: toggleTreeview },
            { name: 'aggregates', checked: false, setter: toggleAggregates },
            { name: 'grouping', checked: false, setter: toggleGrouping}
        ]
    }
];

function derivedPeopleSchema(columns) {
    // create a hierarchical schema organized by alias
    var factory = new Hypergrid.ColumnSchemaFactory(columns);
    factory.organize(/^(one|two|three|four|five|six|seven|eight)/i, { key: 'alias' });
    var columnSchema = factory.lookup('last_name');
    if (columnSchema) {
        columnSchema.defaultOp = 'IN';
    }
    //factory.lookup('birthState').opMenu = ['>', '<'];
    return factory.schema;
}

var customSchema = [
    { name: 'last_name', type: 'number', opMenu: ['=', '<', '>'], opMustBeInMenu: true },
    { name: 'total_number_of_pets_owned', type: 'number' },
    { name: 'height', type: 'number' },
    'birthDate',
    'birthState',
    'employed',
    { name: 'income', type: 'number' },
    { name: 'travel', type: 'number' }
];

var peopleSchema = customSchema;  // or try setting to derivedPeopleSchema

var gridOptions = {
        data: people1,
        schema: peopleSchema,
        margin: { bottom: '17px' }
    },
    grid = window.g = new Hypergrid('div#json-example', gridOptions),
    behavior = window.b = grid.behavior,
    dataModel = window.m = behavior.dataModel,
    idx = behavior.columnEnum;

console.log('Fields:');  console.dir(behavior.dataModel.getFields());
console.log('Headers:'); console.dir(behavior.dataModel.getHeaders());
console.log('Indexes:'); console.dir(idx);

var treeView, dataset;

function setData(data, options) {
    options = options || {};
    if (data === people1 || data === people2) {
        options.schema = peopleSchema;
    }
    dataset = data;
    behavior.setData(data, options);
    idx = behavior.columnEnum;
}

// Preset a default dialog options object. Used by call to toggleDialog('ColumnPicker') from features/ColumnPicker.js and by toggleDialog() defined herein.
grid.setDialogOptions({
    //container: document.getElementById('dialog-container'),
    settings: false
});

// add a column filter subexpression containing a single condition purely for demo purposes
if (false) { // eslint-disable-line no-constant-condition
    grid.getGlobalFilter().columnFilters.add({
        children: [{
            column: 'total_number_of_pets_owned',
            operator: '=',
            operand: '3'
        }],
        type: 'columnFilter'
    });
}

window.vent = false;

//functions for showing the grouping/rollup capabilities
var rollups = window.fin.Hypergrid.analytics.util.aggregations,
    aggregates = {
        totalPets: rollups.sum(2),
        averagePets: rollups.avg(2),
        maxPets: rollups.max(2),
        minPets: rollups.min(2),
        firstPet: rollups.first(2),
        lastPet: rollups.last(2),
        stdDevPets: rollups.stddev(2)
    },
    groups = [idx.BIRTH_STATE, idx.LAST_NAME, idx.FIRST_NAME];

var aggView, aggViewOn = false, doAggregates = false;
function toggleAggregates() {
    if (!aggView){
        aggView = new AggView(grid, {});
        aggView.setPipeline({ includeSorter: true, includeFilter: true });
    }
    if (this.checked) {
        grid.setAggregateGroups(aggregates, groups);
        aggViewOn = true;
    } else {
        grid.setAggregateGroups([], []);
        aggViewOn = false;
    }
}

function toggleTreeview() {
    if (this.checked) {
        treeView = new TreeView(grid, { treeColumn: 'State' });
        treeView.setPipeline({ includeSorter: true, includeFilter: true });
        treeView.setRelation(true, true);
    } else {
        treeView.setRelation(false);
        treeView = undefined;
        delete dataModel.pipeline; // restore original (shared) pipeline
        behavior.setData(); // reset with original pipeline
    }
}

var groupView, groupViewOn = false;
function toggleGrouping(){
    if (!groupView){
        groupView = new GroupView(grid, {});
        groupView.setPipeline({ includeSorter: true, includeFilter: true });
    }
    if (this.checked){
        grid.setGroups(groups);
        groupViewOn = true;
    } else {
        grid.setGroups([]);
        groupViewOn = false;
    }
}

Answer 1

你可以试试：

(rollups.sum(11)).toFixed(2)

括号中的数字似乎使浏览器绕过标识符不能在数字文字后立即开始的限制

编辑#2：

//all formatting and rendering per cell can be overridden in here
dataModel.getCell = function(config, rendererName) {
    if(aggViewOn)
    {
        if(config.columnName == "total_pets")
        {
            if(typeof(config.value) == 'number')
            {
                config.value = config.value.toFixed(2);
            }
            else if(config.value && config.value.length == 3 && typeof(config.value[1]) == 'number')
            {
                config.value = config.value[1].toFixed(2);
            }
        }
    } 
    return grid.cellRenderers.get(rendererName);
};