javascript - 计算特定键的数量

Question

我有这个对象:

"formData": {
    "Total": "60.00",
    "listTable": [],
    "tr0_CC": "KFC",
    "tr0_amount": "10.00",
    "tr1_CC": "SUB",
    "tr1_amount": "20.00",
    "tr2_CC": "WEN",
    "tr2_amount": "30.00"
}

如何仅对 native 或 lodash 的键 tr#_amount 进行计数？在上面的示例中，我应该得到 3。

Answer 1

这是一些标准 (ES6) Javascript:

a = {"formData": {
    "Total": "60.00",
    "listTable": [],
    "tr0_CC": "KFC",
    "tr0_amount": "10.00",
    "tr1_CC": "SUB",
    "tr1_amount": "20.00",
    "tr2_CC": "WEN",
    "tr2_amount": "30.00"
}};

console.log(Object.keys(a.formData).filter(t => t.match(/tr\d+_amount/)).length);