您將希望將數(shù)據(jù)減少為一個(gè)總和。如果它們的鍵等于“食物”，您只會(huì)添加到總和（運(yùn)行總數(shù)）中。
您從零開(kāi)始，并添加解析的整數(shù)（因?yàn)槟魂P(guān)心小數(shù)）價(jià)格每個(gè)具有“食物”鍵的項(xiàng)目。
編輯： reducer的邏輯如下：
TOTAL + (DOES_KEY_MATCH? YES=PARSED_VALUE / NO=ZERO);
const array = [
{ Type: "Food", Price: "100" },
{ Type: "Entertainment", Price: "200" },
{ Type: "Food", Price: "80" },
{ Type: "Entertainment", Price: "150" }
];
/**
* Returns the sum of targeted values that match the key.
* @param data {object[]} - An array of objects.
* @param key {string} - The value of the key that you want to match.
* @param options.keyField [key] {string} - The key field to match against.
* @param options.valueField [value] {string} - The value of the matching item.
* @return Returns the sum of all items' values that match the desired key.
*/
function calculateTotal(data, key, options) {
let opts = Object.assign({ keyField: 'key', valueField: 'value' }, options || {});
return data.reduce((sum, item) => {
return sum + (item[opts.keyField] === key ? parseInt(item[opts.valueField], 10) : 0);
}, 0);
}
console.log('Total cost of Food: $' + calculateTotal(array, 'Food', {
keyField: 'Type',
valueField: 'Price'
}));
如果要處理浮動(dòng)值...
您可以使用parseFloat代替parseInt和格式化數(shù)字toFixed(2)。
const array = [
{ Type: "Food", Price: "100" },
{ Type: "Entertainment", Price: "200" },
{ Type: "Food", Price: "80" },
{ Type: "Entertainment", Price: "150" }
];
function calculateTotal(data, key, options) {
let opts = Object.assign({ keyField : 'key', valueField : 'value' }, options || {});
return data.reduce((sum, item) => {
return sum + (item[opts.keyField] === key ? parseFloat(item[opts.valueField]) : 0);
}, 0);
}
console.log('Total cost of Food: $' + calculateTotal(array, 'Food', {
keyField : 'Type',
valueField : 'Price'
}).toFixed(2));
