Know more about tokens here.
To create a custom token you need to add a function in your file functions.php.
Where the function name will be the filter name.
It has a unique parameter that contains the Token result, it may be a string, an array, an object, or null.
function my_custom_token_filter($data) {
// do whatever you want
return $data;
}
Parameters
The Filters may accept also parameters, the Token's value is automatically passed to the function as the first parameter (or last for some function, like explode).
For example,
substr(0,3)gets the first 3 characters of the returned string;get_the_post_thumbnail('full')gets the full image, not the thumb.
Example
The below function will work as the filter for our token.
function mFunction($data, $data2) {
return $data + $data2;
}
Now, if we have an ACF number field with a value of 50 and key "acf_number", the below custom token will return by computing the value based on function.
[acf:acf_number|mFunction(60)]
Returned value: 50+60 = 110
Note: To use filters, don't forget to use "|"