The defineProperty() and defineProperties() are methods of the JavaScript Object class that can be used to add and modify properties dinamicaly directly on an object.
defineProperty() - Defines a new property, or modifies an existing property of an object, and returns the object.
Object.defineProperty(obj, prop, {
value: Prop_Value,
configurable: true,
enumerable: true
})
- obj - The object on which to define the property.The third argument of this method (with the value of the property) is more complex, with some additional attributes. For a complete documentation see this page: developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Object/defineProperty
// define an object
var sites = {
'CoursesWeb': 'https://coursesweb.net/'
};
// modifies the 'CoursesWeb' property
Object.defineProperty(sites, 'CoursesWeb', {
value: 'https://coursesweb.net/javascript'
});
// adds a new property
Object.defineProperty(sites, 'MarPlo', {
value: 'https://marplo.net/',
configurable: true,
enumerable: true
});
// Test
document.write(sites.CoursesWeb +'<br>'+ sites.MarPlo);
/* Result:
https://coursesweb.net/javascript/
https://marplo.net/
*/
defineProperties() - Sets or modifies multiple existing properties same time directly on an object, returning the object.
Object.defineProperties(obj, {
'prop1': { value: value_prop1 },
'prop2': { value_prop2 },
// ...
})
- obj - The object on which to define or modify properties.
// define an object
var sites = {
'CoursesWeb': 'https://coursesweb.net/html/'
};
// modifies the 'CoursesWeb' property, and adds two new properties
// stores the object in another variable
var sites2 = Object.defineProperties(sites, {
CoursesWeb: { value: 'https://coursesweb.net/' },
MarPlo: { value: 'https://marplo.net/' },
id: { value: 8 }
});
// Test properties in 'sites' and 'sites2'
document.write(sites.CoursesWeb +'<br>'+ sites2.id);
/* Result:
https://coursesweb.net/
8
*/
defineProperty() method. Data selected by the user from Select dropdown list are added as properties into an object, then, the object is displayed as JSON string.
<h4>Example with defineProperty()</h4>
<p>Write a name in the text field, select an Age and Gender.</p>
<div id='showob'>JSON object</div>
<form action='#' method='post'>
Name: <input type='text' name='nmusr' id='nmusr' onkeyup='setObj(this.id, this.value)' /><br>
Age: <select name='agusr' id='agusr' onchange='setObj(this.id, this.value)'>
<option>---</option>
<option value='5-8'>5-8</option>
<option value='9-14'>9-14</option>
<option value='15-20'>15-20</option>
<option value='21-30'>21-30</option>
<option value='31-45'>31-45</option>
</select><br>
Gender: <select name='gdusr' id='gdusr' onchange='setObj(this.id, this.value)'>
<option>---</option>
<option value='male'>Male</option>
<option value='female'>Female</option>
</select>
</form>
<script>
// set 'usrob' with one property
var usrob = {nmusr: 'name'};
// this function adds /modifies property in usrob, using defineProperty()
// converts it into a string, and displays it
function setObj(prop, val) {
Object.defineProperty(usrob, prop, {
value: val,
configurable: true,
enumerable: true
});
document.getElementById('showob').innerHTML = 'JSON object: <b>'+ JSON.stringify(usrob) +'</b>';
}
</script>
<input type="text" name="a_name" value="val" />
h3 {
font-variant: small-caps;
}var msg = "Visit CoursesWeb.net"; alert(msg);
$ip = $_SERVER["REMOTE_ADDR"]; echo $ip;