如果两个值都不存在,我如何推入数组?这是我的数组:
[
{ name: "tom", text: "tasty" },
{ name: "tom", text: "tasty" },
{ name: "tom", text: "tasty" },
{ name: "tom", text: "tasty" },
{ name: "tom", text: "tasty" }
]
如果我试图再次推入数组的名字:“tom”或文本:“tasty”,我不希望发生任何事情…但如果这两个都不存在那么我就输入。push()
我该怎么做呢?
这个问题有点老了,但我的选择是
let finalTab = [{id: 1, name: 'dupont'}, {id: 2, name: 'tintin'}, {id: 3, name:'toto'}]; // Your array of object you want to populate with distinct data
const tabToCompare = [{id: 1, name: 'dupont'}, {id: 4, name: 'tata'}]; // A array with 1 new data and 1 is contain into finalTab
finalTab.push(
...tabToCompare.filter(
tabToC => !finalTab.find(
finalT => finalT.id === tabToC.id)
)
); // Just filter the first array, and check if data into tabToCompare is not into finalTab, finally push the result of the filters
console.log(finalTab); // Output : [{id: 1, name: 'dupont'}, {id: 2, name: 'tintin'}, {id: 3, name: 'toto'}, {id: 4, name: 'tata'}];
不确定速度,但stringification + indexOf是一个简单的方法。首先将数组转换为字符串:
let strMyArray = JSON.stringify(myArray);
然后,对于一系列属性-值对,您可以使用:
if (strMyArray.indexOf('"name":"tom"') === -1 && strMyArray.indexOf('"text":"tasty"') === -1) {
myArray.push({ name: "tom", text: "tasty" });
}
查找整个对象更简单:
if (strMyArray.indexOf(JSON.stringify(objAddMe) === -1) {
myArray.push(objAddMe);
}
推动动态
var a = [
{name:"bull", text: "sour"},
{name: "tom", text: "tasty" },
{name: "Jerry", text: "tasty" }
]
function addItem(item) {
var index = a.findIndex(x => x.name == item.name)
if (index === -1) {
a.push(item);
}else {
console.log("object already exists")
}
}
var item = {name:"bull", text: "sour"};
addItem(item);
用简单的方法
var item = {name:"bull", text: "sour"};
a.findIndex(x => x.name == item.name) == -1 ? a.push(item) : console.log("object already exists")
如果数组只包含基元类型/简单数组
var b = [1, 7, 8, 4, 3];
var newItem = 6;
b.indexOf(newItem) === -1 && b.push(newItem);
如果不在列表中,则添加
对于一个简单值的列表,它是一行程序…
[...new Set([...someArray, someElement])]
JavaScript的用法:
var myArray = ['bill','bob']
var alreadyIn = [...new Set([...myArray, 'bob'])] // ['bill','bob']
var notAlreadyIn = [...new Set([...myArray, 'peter'])] // ['bill','bob','peter']
TypeScript文本(注意include vs includes):
interface Array<T> {
include(element: T): Array<T>
}
Array.prototype.include = function (element: any): any[] {
return [...new Set([...this, obj])]
}
...但对于对象来说,情况就复杂多了
[...new Set([...someArray.map((o) => JSON.stringify(o)),
JSON.stringify(someElement)]).map((o) => JSON.parse(o))
TypeScript文本处理任何事情:
Array.prototype.include = function (element: any): any[] {
if (element && typeof element === 'object')
return [
...new Set([
...this.map((o) => JSON.stringify(o)),
JSON.stringify(element),
]),
].map((o) => JSON.parse(o))
else return [...new Set([...this, element])]
}
我有这个问题,我做了一个简单的原型,使用它,如果你喜欢它
Array.prototype.findOrPush = function(predicate, fallbackVal) {
let item = this.find(predicate)
if(!item){
item = fallbackVal
this.push(item)
}
return item
}
let arr = [{id: 1}]
let item = arr.findOrPush(e => e.id == 2, {id: 2})
console.log(item) // {id: 2}
// will not push and just return existing value
arr.findOrPush(e => e.id == 2, {id: 2})
conslog.log(arr) // [{id: 1}, {id: 2}]