如何确定JSON对象是否有属性，如果有，属性值是否大于0

Question

我有一些从API返回的JSON，类似于：

{"amount_to_collect":0,"breakdown":{"city_tax_collectable":0,"city_tax_rate":0,"city_taxable_amount":0,"combined_tax_rate":0,"county_tax_collectable":0,"county_tax_rate":0,"county_taxable_amount":0,"line_items":[{"city_amount":0,"city_tax_rate":0,"city_taxable_amount":0,"combined_tax_rate":0,"county_amount":0,"county_tax_rate":0,"county_taxable_amount":0,"id":"1","special_district_amount":0,"special_district_taxable_amount":0,"special_tax_rate":0,"state_amount":0,"state_sales_tax_rate":0,"state_taxable_amount":0,"tax_collectable":0,"taxable_amount":0}],"special_district_tax_collectable":0,"special_district_taxable_amount":0,"special_tax_rate":0,"state_tax_collectable":0,"state_tax_rate":0,"state_taxable_amount":0,"tax_collectable":0,"taxable_amount":0}}

我需要检查"；amount_to_collect"；存在，并且如果它确实检查该值是否大于0，包括任何美分，则IE 0.01应该更大。

我可以用检查它是否存在

if (data.hasOwnProperty("amount_to_collect"))

我可以用检查它是否大于零

if(data.amount_to_collect == 0) {
alert('zero');
} else if(data.amount_to_collect > 0) {
alert('greater')
}

但无法弄清楚如何检查它是否存在，以及它是否存在的值是否大于零。在某些情况下，它可能不会被退回，我需要有一个理由。

Answer 1

tax将只包含hasOwnProperty()的布尔结果。在您的示例中，给定的对象将永远是true，因此您总是看到"更大"的输出。

要解决此问题，您需要将包含检查属性是否存在的结果的变量与属性本身的值分开。试试这个：

let data = {
"amount_to_collect": 0
// other properties...
}
var propertyExists = data.hasOwnProperty("amount_to_collect");
if (propertyExists && data.amount_to_collect > 0) {
console.log('greater');
} else {
console.log('less');
}