This is my object data:
[{id:1, name:"Cat", category:{id:2, name:"Animals"}}]
I want to check if it contains the key category.
This is my approach:
if (data.hasOwnProperty("category")) {
console.log("data contains category");
}else {
console.log("data does not contain category");
}
The output is:
data does not contain category
Should be the opposite...
You need to iterate your array. So you can put the code inside a forEach
let k = [{
id: 1,
name: "Cat",
category: {
id: 2,
name: "Animals"
}
}]
k.forEach(function(data) {
if (data.hasOwnProperty("category")) {
console.log("data contains category");
} else {
console.log("data does not contain category");
}
})If you dont prefer to iterate you need to pass the index , since data is an array of object.
let data = [{
id: 1,
name: "Cat",
category: {
id: 2,
name: "Animals"
}
}]
if (data[0].hasOwnProperty("category")) {
console.log("data contains category");
} else {
console.log("data does not contain category");
}You can also use some to check if any object in your array matches a certain condition:
var data = [{
id: 1,
name: "Cat",
category: {
id: 2,
name: "Animals"
}
}];
var hasCategory = data.some(k => k.hasOwnProperty('category'));
if (hasCategory) {
console.log("data contains category");
} else {
console.log("data does not contain category");
}You need to loop through array elements. and you can destructure assignment
let arr = [{id:1, name:"Cat", category:{id:2, name:"Animals"}}]
arr.forEach(({category})=>{
if (category !== undefined) {
console.log("data contains category");
}else {
console.log("data does not contain category");
}
})
category is defined to null, 0, or any other falsy value, your current code will display: data does not contain category. Maybe you can improve it changing the check condition to category !== undefined.
That's an array with only one index, so you can do this using the operator in:
"category" in data[0] // That checks if the property "category" exists.
If you have more than one index, you should loop that array.
The operator in also checks for inherited properties.
let data = [{id:1, name:"Cat", category:{id:2, name:"Animals"}}];
data.forEach((o, i) => console.log("Index:", i, " - Has category?:", "category" in o));
data.alert(data.toString());this is the ouput:[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object][ ]around an object; it's an array with one object in it.