Javascript 如何使用javascript检查对象中是否存在值

How to check if value exists in object using javascript

提问by Brown KL

I have an object in javascript

我在 javascript 中有一个对象

var obj = {
   "a": "test1",
   "b": "test2"
}

How do I check that test1 exists in the object as a value?

如何检查 test1 是否作为值存在于对象中？

回答by Matt Pileggi

You can turn the values of an Object into an array and test that a string is present. It assumes that the Object is not nested and the string is an exact match:

您可以将对象的值转换为数组并测试字符串是否存在。它假设对象没有嵌套并且字符串是完全匹配的：

var obj = { a: 'test1', b: 'test2' };
if (Object.values(obj).indexOf('test1') > -1) {
   console.log('has test1');
}

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/values

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/values

回答by tymeJV

You can use the Array method .some:

您可以使用数组方法.some：

var exists = Object.keys(obj).some(function(k) {
    return obj[k] === "test1";
});

回答by jcubic

try:

尝试：

var obj = {
   "a": "test1",
   "b": "test2"
};
Object.keys(obj).forEach(function(key) {
  if (obj[key] == 'test1') {
    alert('exists');
  }
});

or

或者

var obj = {
   "a": "test1",
   "b": "test2"
};
var found = Object.keys(obj).filter(function(key) {
  return obj[key] === 'test1';
});
if (found.length) {
   alert('exists');
}

UPDATEthis will not work for NaNand -0for those values, you can use (instead of ===) new in ES6:

UPDATE这不会工作NaN，并-0为这些值，你可以使用（而不是===在ES6）新：

 Object.is(obj[key], value);

UPDATE

更新

With modern browsers you can also use:

使用现代浏览器，您还可以使用：

var obj = {
   "a": "test1",
   "b": "test2"
};
if (Object.values(obj).includes('test1')) {
  alert('exists');
}

回答by isvforall

Use for...inloop:

使用for...in循环：

for (let k in obj) {
    if (obj[k] === "test1") {
        return true;
    }
}

回答by Dangerousmouse

You can use Object.values():

您可以使用Object.values()：

The Object.values()method returns an array of a given object's own enumerable property values, in the same order as that provided by a for...inloop (the difference being that a for-in loop enumerates properties in the prototype chain as well).

该Object.values()方法返回给定对象自己的可枚举属性值的数组，其顺序与for...in循环提供的顺序相同 （区别在于 for-in 循环也枚举原型链中的属性）。

and then use the indexOf()method:

然后使用indexOf()方法：

The indexOf()method returns the first index at which a given element can be found in the array, or -1 if it is not present.

该indexOf()方法返回可以在数组中找到给定元素的第一个索引，如果不存在，则返回 -1。

For example:

例如：

Object.values(obj).indexOf("test`") >= 0

A more verbose example is below:

一个更详细的例子如下：

var obj = {
  "a": "test1",
  "b": "test2"
}


console.log(Object.values(obj).indexOf("test1")); // 0
console.log(Object.values(obj).indexOf("test2")); // 1

console.log(Object.values(obj).indexOf("test1") >= 0); // true
console.log(Object.values(obj).indexOf("test2") >= 0); // true 

console.log(Object.values(obj).indexOf("test10")); // -1
console.log(Object.values(obj).indexOf("test10") >= 0); // false

回答by chickens

Shortest ES6+ one liner:

最短的 ES6+ 单线：

let exists = Object.values(obj).includes("test1");

回答by DarckBlezzer

I did a test with this all examples, I ran this in nodejs v8.11.2, take this as guide to select your best choice.

我对所有示例进行了测试，我在nodejs v8.11.2 中运行了它，以此作为选择最佳选择的指南。

let i,tt;
 const obj = { a: 'test1', b: 'test2' , c: 'test3' , d: 'test4' , e: 'test5' , f: 'test6' };
 
console.time("test1")
i=0;
for(;i<1000000;i=i+1){
  if (Object.values(obj).indexOf('test4') > -1) {
    tt = true;
  }
}
console.timeEnd("test1")

console.time("test1.1")
i=0;
for(;i<1000000;i=i+1){
  if (~Object.values(obj).indexOf('test4')) {
    tt = true;
  }
}
console.timeEnd("test1.1")

console.time("test2")
i=0;
for(;i<1000000;i=i+1){
  if (Object.values(obj).includes('test4')) {
    tt = true;
  }
}
console.timeEnd("test2")


console.time("test3")
i=0;
for(;i<1000000;i=i+1){
  for(const item in obj){
    if(obj[item] == 'test4'){
      tt = true;
      break;
    }
  }
}
console.timeEnd("test3")

console.time("test3.1")
i=0;
for(;i<1000000;i=i+1){
  for(const [item,value] in obj){
    if(value == 'test4'){
      tt = true;
      break;
    }
  }
}
console.timeEnd("test3.1")


console.time("test4")
i=0;
for(;i<1000000;i=i+1){
  tt = Object.values(obj).some( (val,val2) => {
    return val == "test4" 
  }); 
}
console.timeEnd("test4")

console.time("test5")
i=0;
for(;i<1000000;i=i+1){
  const arr = Object.keys(obj);
  const len = arr.length;
  let i2=0;
  for(;i2<len;i2=i2+1){
    if(obj[arr[i2]]=="test4"){
      tt = true;
      break;
    }
  }
}
console.timeEnd("test5")

Output in my server

在我的服务器中输出

test1: 272.325ms
test1.1: 246.316ms
test2: 251.980ms
test3: 73.284ms
test3.1: 102.029ms
test4: 339.299ms
test5: 85.527ms

回答by Joshua Shibu

for one liner I would say

对于一个班轮我会说

exist=Object.values(obj).includes("test1");
console.log(exist);

回答by Yokki vallayok

You can try this:

你可以试试这个：

function checkIfExistingValue(obj, key, value) {
    return obj.hasOwnProperty(key) && obj[key] === value;
}
var test = [{name : "Hyman", sex: F}, {name: "joe", sex: M}]
console.log(test.some(function(person) { return checkIfExistingValue(person, "name", "Hyman"); }));

回答by Devang Hire

 getValue = function (object, key) {
    return key.split(".").reduce(function (obj, val) {
      return (typeof obj == "undefined" || obj === null || obj === "") ? obj : (_.isString(obj[val]) ? obj[val].trim() : obj[val]);}, object);
};

var obj = {
   "a": "test1",
   "b": "test2"
};

function called

调用的函数

 getValue(obj,"a");