如何检查数组的所有对象是否包含在另一个数组中？

Question

我试图检查对象array A包含来自B objects 。

let A = [
    { name: "Max" },
    { name: "Jhon" },
    { name: "Naton" },
]

let B = [
    { name: "Max" },
    { name: "Naton" },
]

所以B有两个objects在array A 。 怎么检查这个？

我试图通过includes ：

  for(let entry of this.b){
      if(this.a.includes(entry)){
        console.log('includes');
      }
    }

但是我对includes false 。

Answer 1

您必须使用另一个循环，然后检查属性名称：

 var a = [ {name: "Max"}, {name: "Jhon"}, {name: "Naton"}, ]; var b = [ {name: "Max"}, {name: "Naton"}, ]; for(let entry of b){ for(let entry2 of a){ if(entry2.name == entry.name){ console.log('includes', entry.name); } } } 

或者：您可以使用对象的字符串版本来检查includes() ：

 var a = [ {name: "Max"}, {name: "Jhon"}, {name: "Naton"}, ]; var b = [ {name: "Max"}, {name: "Naton"}, ]; var aTemp = a.map(i => JSON.stringify(i)); var bTemp = b.map(i => JSON.stringify(i)); for(let entry of bTemp){ if(aTemp.includes(entry)){ console.log('includes', entry); } } 

Answer 2

方法Array.includes()将数组的条目与给定值进行比较。 因为您的数组条目是对象，所以它不匹配。 你必须自己循环数组并进行比较。

Array.some()在数组上循环，如果返回true至少为1，则返回true。 当您想要验证某些内容时，此方法很有用。 在我们的示例中，我们要验证数组a是否包含b条目。

 const a = [{ name: 'Max', }, { name: 'Jhon', }, { name: 'Naton', }, ]; const b = [{ name: 'Max', }, { name: 'Naton', }, { name: 'Daddy', }, ]; console.log(b.map(x => a.some(y => y.name === x.name))); 

---

如果我把它分解：

 const a = [{ name: 'Max', }, { name: 'Jhon', }, { name: 'Naton', }, ]; const b = [{ name: 'Max', }, { name: 'Naton', }, { name: 'Daddy', }, ]; // Loop on every entry of the b array b.forEach((x) => { // x here represent one entry // first it will worth { name: 'Max' }, then { name: 'Naton' } ... // for each value we are going to look at a if we can find a match const isThereAMatch = a.some((y) => { // y here is worth one entry of the a array if (y.name === x.name) return true; return false; }); if (isThereAMatch === true) { console.log(`We have found ${x.name} in a`); } else { console.log(`We have not found ${x.name} in a`); } }); 

Answer 3

当您使用Array#includes()方法时 ，它将始终返回false 因为它正在比较不相等的objects ，因为它们没有引用同一个object 。

您应该比较对象properties而不是整个对象，您可以使用Array#some()方法来执行此操作，如下所示：

for (let entry of this.b) {
  if (this.b.some(x => x.name === entry.name)) {
    console.log('includes');
  }
}

演示：

 A = [{ name: "Max" }, { name: "Jhon" }, { name: "Naton" }, ] B = [{ name: "Max" }, { name: "Naton" }, ] //Filter objects that exists in both arrays let result = A.filter(el=> B.some(x => x.name === el.name)); console.log(result);