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How to Check If an Object Property is Undefined in JavaScript
source link: https://www.laravelcode.com/post/how-to-check-if-an-object-property-is-undefined-in-javascript
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How to Check If an Object Property is Undefined in JavaScript
Use the strict equality operator (===)
You can use the typeof operator in combination with the strict equality operator (===) to check or detect if a JavaScript object property is undefined.
Let's take a look at the following example to understand how it actually works:
<script>
var person = {
name: "Clark",
age: 32,
country: "United States"
};
// Access an existing object property
console.log(person.age); // Prints: 32
// Detect if object property is undefined
if(typeof person.gender === "undefined"){
console.log("This property is not defined.");
}
</script>
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