我需要数组中对象的索引,以便我可以删除数组的这一部分。我尝试使用这个:
var index = this.urenRegistratie.indexOf(newDatum);
但它一直返回-1,我不知道为什么会发生这种情况。
这是我的代码的一部分。它从 html 表单中获取数据并将其放入我的数组中,现在我已经准备好了 if 语句( exisitingDatum ),我的代码需要位于其中。有人可以帮我一下吗?
store(newValue:number, newDatum, newAanwezig, newComment){
const existingDatum = this.urenRegistratie.find(billable => {
return billable.datum === newDatum;
return
});
if (!existingDatum) {
let billable = new BillableHours();
billable.datum = newDatum;
billable.hours = +newValue;
billable.aanwezig = newAanwezig;
billable.comment = newComment;
if(billable.aanwezig == "Aanwezig" && billable.hours !== 0 && billable.datum !== null) {
this.urenRegistratie.push(billable);
}
}
if(existingDatum) {
}
}
findIndex() 方法返回数组中第一个元素的索引 满足所提供的测试功能的数组。否则,它 返回-1,表示没有元素通过测试。
如果您有这样的对象数组,请尝试使用
findIndex
:
const a = [
{ firstName: "Adam", LastName: "Howard" },
{ firstName: "Ben", LastName: "Skeet" },
{ firstName: "Joseph", LastName: "Skeet" }
];
const index = a.findIndex(x => x.LastName === "Skeet");
console.log(index);
添加@StepUp的答案(请选择他的最佳答案,因为它很好地回答了问题):
查找索引与 Angular 无关,而是 Vanilla JavaScript。
在您的情况下,您需要一个以
newDatum
“needle” 作为参数的函数,以便使用 findIndex: 在数组“haystack”中搜索
var getNewDatumIndex = (array, newDatumNeedle) => {
return array.findIndex(x => x.newDatum === newDatumNeedle);
}
如果需要,您还可以在数组原型中添加方法,以省略第一个参数:
Array.prototype.getNewDatumIndex = (newDatumNeedle) => {
return this.findIndex(x => x.newDatum === newDatumNeedle);
}
一个简单而优雅的解决方案是使用 _.isEqual,它使用 lodash 库
执行深度比较Npm 包 -- https://www.npmjs.com/package/lodash
const a = [
{ firstName: "Adam", LastName: "Howard" },
{ firstName: "Ben", LastName: "Skeet" },
{ firstName: "Joseph", LastName: "Skeet" }
];
const find = { firstName: "Joseph", LastName: "Skeet" }
index = a.findIndex(x => _.isEqual(x, find));
console.log(index);
store(newValue: number, newDatum, newAanwezig, newComment) { 让索引 = this.urenRegistratie.indexOf(existingDatum);
const existingDatum = this.urenRegistratie.find(billable => {
return billable.datum === newDatum;
return
});
if (index != -1) {
let index = this.urenRegistratie.indexOf(existingDatum);
existingDatum.splice(index, 1)
} else {
let billable = new BillableHours();
billable.datum = newDatum;
billable.hours = +newValue;
billable.aanwezig = newAanwezig;
billable.comment = newComment;
if (billable.aanwezig == "Aanwezig" && billable.hours !== 0 && billable.datum !== null) {
this.urenRegistratie.push(billable);
}
}
}
let arr = [6, 4, 9, 5, 56, 7];
let selectedNumber = 9;
// Find the index of the selected number
let index = arr.indexOf(selectedNumber);
if (index !== -1) {
// Get previous and next values
let previousValue = index > 0 ?
arr[index - 1] : undefined; // If it
exists
let nextValue = index < arr.length - 1 ?
arr[index + 1] : undefined; // If it
exists
console.log(`Previous: ${previousValue},
Next: ${nextValue}`);
} else {
console.log("Selected number not
found.");
}
有时候,如果你通过id进行比较,你需要解析,因为对象的id是一个字符串。照顾这个