Comparing a user supplied string to a string on the data object

[tzaitoun]

I'm trying to implement a way to filter out objects based on the user supplied string. I wanted to string match using a fuzzy match algorithm, but when defining a custom function:

fuzzy(inputString, matchString) {
   // return boolean
}

and setting the filter expression to this (example data object: { name: 'John K', age: 18 }):
fuzzy(name, 'John')

doesn't pass 'John' to the custom function. Is there a way to do this?

[cshaa]

Hey Talat!
Sorry for the late reply! The problem with your code is that you use single quotes – by looking at the Readme, you can see that strings in Filtrex use double quotes while single quotes are reserved for symbols. In your case, all four of these are identical:

• fuzzy(name, John)
• fuzzy('name', John)
• fuzzy(name, 'John')
• fuzzy('name', 'John')

What you actually want is:

fuzzy(name, "John")

[cshaa]

You might also be interested in operator overloading which will be added in Filtrex v3. You can already use it, as v3 has a release candidate on NPM.

import { compileExpression } from "filtrex";

const options = {
    operators: {
        '~=': function fuzzy(a, b) { return a.toLowerCase().includes(b.toLowerCase()) }
    }
};

const expr = `name ~= "john"`;
const f = compileExpression(expr, options);

f({ name: "John Doe"}) // true
f({ name: "Jane Smith"}) // false

Try it.

[cshaa]

Also: v3 has better error discoverability. If you run your original code in v3, you'll get an UnknownPropertyError, as you should:

[tzaitoun]

Thank you, this was very helpful. I'll definitely check v3 out.

[cshaa]

Update: I've finally published v3 as a stable release. Therefore you don't have to worry about release candidates and the like :)