JavaScript Check if Map contains a Specific Key
To check if Map contains a specific key in JavaScript, call has() method on this map and pass the specific key as argument to it.
has() method returns a boolean value. The return value is true
if the key is present in the map, else, false
.
Syntax
The syntax to check if specific key key
is present in a Map map
using has() method is
map.has(key)
Examples
In the following example, we take a Map with keys 'a'
, 'b'
, and 'c'
. We shall check if the key 'b'
is present in this Map using has() method.
index.html
<!DOCTYPE html> <html lang="en"> <body> <pre id="output"></pre> <script> var map1 = new Map([ ['a', 10], ['b', 20], ['c', 30] ]); var result = map1.has('b'); var displayOutput = 'Is the key present in Map? ' + result + '\n\n'; document.getElementById('output').innerHTML += displayOutput; </script> </body> </html>
Now, let us check if a key ‘x’ is present in this map.
index.html
<!DOCTYPE html> <html lang="en"> <body> <pre id="output"></pre> <script> var map1 = new Map([ ['a', 10], ['b', 20], ['c', 30] ]); var result = map1.has('x'); var displayOutput = 'Is the key present in Map? ' + result + '\n\n'; document.getElementById('output').innerHTML += displayOutput; </script> </body> </html>
Conclusion
In this JavaScript Tutorial, we learned how to check if a specific key is present in a Map in JavaScript using has() method, with examples.