Data Expressions for JavaScript
data-expression
makes working with statically evaluable JavaScript
expressions safely (specifically, not using eval()
)... fun, maybe? This
could come in handy if you're making something that allows users to filter, map
or manipulate data. Here are some examples:
The data-expression
module's evaluate()
function takes an
expression and an optional object of variable values:
> var datex = ;> ;3
The setter()
function takes an assignment statement and evaluates
it in the context of the provided object, then returns the modified
object:
> var setter = ;> ;foo: 20
Leaving off the second argument returns a function that can be
re-evaluated with different data values. In this example, you can see that
we're using ES6 arrow functions as a shorthand for
function(x) { return x * 10 }
:
> var expr = ;> ;30 20 10
These evaluation context functions can have variables set programmatically,
and you can even require()
modules for use in the expression:
> var context = ;> ;foo: 'Foo bar'
The CLI tool
Think of this as an enabler of one-line data transforms.
Reformat dates in a dat repository:
$ dat cat | datex --require 'moment' - \ "date = moment(date).format('YYYY-MM-DD')" | dat