Keep rules like order.total >= 50 as text, in your config, your database, or your users' hands. Bonsai checks them against your types, runs them safely, and explains every result.
v1.3.1, MIT licence, zero dependencies
Expression
order.total >= 50 && customer.tier == "gold"
Edit it, or hover any part.
Data
order{ total: 84.5, country: "NZ" }customer{ tier: "gold" }Result
Ships free
true boolean
ordertruecustomertrueTell Bonsai what an expression can read.
const env = bonsai({
variables: { total: t.number() },
})Catch typos and wrong types when the rule is saved.
const rule = env.compile('total >= 50')
// throws on a typo or a wrong typeAgainst real data, as often as you like.
rule.evaluateSync({ total: 84.5 })
// trueChecked against your types, with a fix where there is one.
| Someone writes | Bonsai says |
|---|---|
order.totl > 100 | did you mean "total"? |
order.total >= "50" | can't compare a number with text |
user.email.endsWith("@acme") | email may be missing |
order.country == "UK" | never true: country is NZ, AU, US or GB |
explain() tells you why, for every order.
order
| Order | Result | Why |
|---|---|---|
| 120 to US | Pays | order.country == "NZ" false |
| 84.5 to NZ | Ships free | order.total >= 50 trueorder.country == "NZ" true |
| 19.9 to GB | Pays | order.total >= 50 falseorder.country == "NZ" false |
It reads only the data you pass in: no reaching your app, changing data, endless loops, or runaway memory.
| Someone tries | Blocked |
|---|---|
user.constructor | No way into JavaScript |
user.role = "admin" | Expressions only read, never change data |
"ab".repeat(1e9) | Stopped at the size limit |
Translated to a query, so the database does the filtering.
orderWHERE ((`total` >= ?1) AND (`country` IN (?2, ?3)))?1 = 50, ?2 = "NZ", ?3 = "AU"If the same rules must also run in Go or Java, use CEL. For a visual builder that stores JSON, use json-logic.
| Library | Rules are | Checked against types | Suggests fixes | Explains results | Filters a database | Browser, gzip |
|---|---|---|---|---|---|---|
| bonsai-js | Text, JS-like | Yes | Yes | Yes | Yes | 29.0 KB 69.2 KB checking in the browser |
| cel-js | Text, CEL | Yes | No | No | No | 24.3 KB |
| json-logic-js | JSON | No | No | No | No | 2.0 KB |
| jexl | Text, JS-like | No | No | No | No | 6.1 KB |
| filtrex | Text, own syntax | No | No | No | No | 7.8 KB |
Bonsai's 29.0 KB is for rules checked on a server. The full comparison covers nine libraries, what each part of Bonsai's size buys, and when each library is the better choice.
Five minutes from install to your first checked rule.