I have a function that accepts a function parameter that I'd like to use as the key to an object...
function foo(func) {
return { func: true };
}
This, of course, returns an object with the string 'func' as the key (not what I want).
Is the right solution to create a string from func and then create the object?
Is there a way to create a hash from a function?
Bearing in mind that object keys are always strings you should be able to use this syntax:
result = {};
result[func] = true;
return result;
Though you can use functions as keys directly, you can use a hash code function to get the string representation of the function to create integer keys. I got one from http://erlycoder.com/49/javascript-hash-functions-to-convert-string-into-integer-hash-.
function hashFunc(func){
var str = func.toString();
var hash = 0;
if (str.length == 0) return hash;
for (i = 0; i < str.length; i++) {
char = str.charCodeAt(i);
hash = ((hash<<5)-hash)+char;
hash = hash & hash; // Convert to 32bit integer
}
console.log(hash);
return hash;
}
var col = {}
function add(func) {
col[hashFunc(func)] = true;
}
function get(func) {
return col[hashFunc(func)] || false;
}
// test
add(hashFunc);
console.log(get(add)); // false
console.log(get(hashFunc)); // true
