revision:
The Object.defineProperties() static method defines new or modifies existing properties directly on an object, returning the object.
Object.defineProperties(obj, props)
Parameters:
obj : required. The object on which to define or modify properties.
props : required . An object whose keys represent the names of properties to be defined or modified and whose values are objects describing those properties. Each value in props must be either a data descriptor or an accessor descriptor; it cannot be both.
const object1 = {};
Object.defineProperties(object1, {
property1: {
value: 42,
writable: true
},
property2: {}
});
console.log(object1.property1);
// Expected output: 42
<div>
<p id="obj-1"></p>
<p id="obj-2"></p>
<p id="obj-3"></p>
</div>
<script>
const obj = {};
Object.defineProperties(obj, {
property1: {
value: true,
writable: true,
},
property2: {
value: "Hello",
writable: false,
},
// etc. etc.
});
document.getElementById("obj-1").innerHTML = "properties defined : " + obj.property1;
document.getElementById("obj-2").innerHTML = "properties defined : " + obj.property2;
document.getElementById("obj-3").innerHTML = "properties defined : " + obj.property2.writable;
</script>
<div>
<p id="obj-4"></p>
<p id="obj-5"></p>
<p id="obj-6"></p>
<p id="obj-7"></p>
</div>
<script>
const object1 = {};
Object.defineProperties(object1, {
prop1: {
value: "JavaScript",
writable: true,
},
prop2: {
value: "TypeScript",
writable: false,
},
});
console.log(object1.prop1); // JavaScript
console.log(object1.prop2); // TypeScript
// This works since prop1 is writable
document.getElementById("obj-4").innerHTML = "properties defined : " + object1.prop1;
document.getElementById("obj-5").innerHTML = "properties defined : " + object1.prop2;
object1.prop1 = "React";
console.log(object1.prop1); // React
document.getElementById("obj-6").innerHTML = "properties defined : " + object1.prop1;
// TypeError: Cannot assign to read only property 'prop2' of object '#<Object>'
object1.prop2 = "Node";
console.log(object1.prop2); // TypeScript
document.getElementById("obj-7").innerHTML = "properties defined : " + object1.prop2;
</script>