The method handler.has is utilized to "conceal" any property desired. It acts as a trap for an operator. This method returns a Boolean value of true if access to the property is permitted; otherwise, it returns false based on whether the key exists within the original object or not.
Syntax
Example
has: function(target, prop)
Parameters
target : The target object.
prop : The property to check for existence.
Return value
Return a Boolean value.
Browser Support
| Chrome | 49 |
|---|---|
Edge |
12 |
| Firefox | 18 |
| Opera | 36 |
Example 1
Example
const x = { f:10 };
const proxy = new Proxy(x, {
has: function(target, name) {
document.writeln('in has');
//expected output: in has
return name in target;
}
});
document.writeln('f' in proxy);
//expected output: true
Output:
Output
in has true
Example 2
Example
var x={hoo:1}
var xyz = new Proxy(x, {
has: function(target, key) {
if(key == "a") return false;
return true;
}
}
)
var x= ("a" in xyz)
var y = ("b" in xyz)
document.write("a in d: " +x)
//expected output: a in d: false
document.write('<br/>');
document.write("b in d: " +y)
//expected output: b in d: true
Output:
Output
a in d: false
b in d: true
Example 3
Example
var s={
voo:1
}
var p = new Proxy(s, {
has: function(target, prop) {
document.writeln('called: ' + prop);
return false;
}
});
document.writeln('a' in p);
//expected output:called: a false
Output:
Output
called: a false
