Customizing MathJS

You may find yourself wanting to add functionality to the math view fields. And as they use mathjs internally, you actually can!

Importing new options into mathJS

The mathjs library allows the user to define his own functions and constants, as described in their documentation.

To leverage that, Meta Bind exposed its mathjs instance for you to modify. The most sensible place to do this, is inside a JS Engine startup script. This ensures the modifications are loaded early and will be immediately available when the first documents gets rendered.

Caution

Modifying mathJS via a js-engine codeblock inside a document may cause timing problems and is not recommended!

Adding a custom function clamp

As an example, we will define a clamp() function, which is not part of default mathJS, but can be very helpful. The function should take in three parameters, the current value, a minimum, and a maximum. It returns the current value as long as its inside the range otherwise the boundary-value.

clamp: (val, min, max) => Math.min(Math.max(min, val), max);

Add this definitions inside a JavaScrypt file stored in you Vault and enable that file to be run as a startup script. Inside the file you can use the mathJSImport(dict, options) function from the API to import you definitions into mathjs.

const mb = engine.getPlugin('obsidian-meta-bind-plugin').api;

mb.mathJSImport({
    // definition of the clamp function
    clamp: (val, min, max) => Math.min(Math.max(min, val), max),

    // we can also define useful constants here
    foo: 42,
});

Now you can use this newly defined function in a view field. This example will always display values between 0 and 10, even if num gets outside that range.

VIEW[clamp({num}, 0, 10)]

You can also use the new constant foo. The following example will display 52.

VIEW[foo + 10]