我有一个数组:
[
{
theme: "low battery",
Number: "S-10",
components: [ "hardware", "battery" ]
},
{
theme: "bad sync",
Number: "S-11",
components: [ "software" ]
},
{
theme: "misc troubles",
Number: "S-12",
components: [ "hardware", "software" ]
}
]
所以我想用"组件"对这个数组进行分组。值。换句话说,我想知道组件在组件中出现的次数。例如:
[
{
component: "hardware",
amount: 2
},
{
component: "software",
amount: 2
},
{
component: "battery",
amount: 1
}
]
答案 0 :(得分:1)
您可以创建一个地图以有效的方式存储每个组件的数量(查找O(1)的复杂度):
var items = [
{
theme: "low battery",
Number: "S-10",
components: [ "hardware", "battery" ]
},
{
theme: "bad sync",
Number: "S-11",
components: [ "software" ]
},
{
theme: "misc troubles",
Number: "S-12",
components: [ "hardware", "software" ]
}
];
var componentMap = new Map();
items.forEach((item) => {
item.components.forEach((component) => {
if (componentMap.has(component)) {
componentMap.set(component, componentMap.get(component) + 1);
}
else {
componentMap.set(component, 1);
}
});
});
var componentCount = [];
componentMap.forEach((value, key) => {
componentCount.push({
component: key,
amount: value
});
});
console.log(componentCount);

答案 1 :(得分:1)
var arr = [
{
theme: "low battery",
Number: "S-10",
components: [ "hardware", "battery" ]
},
{
theme: "bad sync",
Number: "S-11",
components: [ "software" ]
},
{
theme: "misc troubles",
Number: "S-12",
components: [ "hardware", "software" ]
}
];
var components = {};
arr.forEach(function(val){
val.components.forEach(function(c){
components[c] = !(c in components) ? 1 : Number(components[c])+1;
});
});
var componentCount = [];
for(key in components){
componentCount.push({'component' : key, 'amount' : components[key]});
}
console.log(componentCount);
答案 2 :(得分:1)
您可以使用forEach()
循环和thisArg
参数来存储每个组件并增加金额。
var data = [{"theme":"low battery","Number":"S-10","components":["hardware","battery"]},{"theme":"bad sync","Number":"S-11","components":["software"]},{"theme":"misc troubles","Number":"S-12","components":["hardware","software"]}]
var result = []
data.forEach(function(e) {
var that = this;
e.components.forEach(function(c) {
if(!that[c]) {
that[c] = {component: c, amount: 0}
result.push(that[c])
}
that[c].amount += 1
})
}, {})
console.log(result)