3xpr

3xpr

Js-expression is an extensible expression evaluator and parser.

Besides the operators, functions, variables, objects and arrays that are supported.

It is possible to extend it with your own functions, operators, etc

Features

• Constants, enums, number, string, datetime, variables, objects and array
• Arithmetic , assignment , comparison , logical and bitwise operators
• Number , string , datetime , array and nullable functions
• Conversion functions
• Arrow functions
• Group functions (distinct, first, last, min, max, sum and avg)
• Sets functions (union, intersection, difference and symmetric difference)
• Control flows flows
• Environment variables
• Extend
• Metadata

Quick start

import { expressions as exp } from '3xpr'

const context = {
name: 'Spain',
region: 'Europe',
phoneCode: '34',
timezones: [
	{ name: 'Madrid', offset: 1, pos: { lat: 40.4165, log: -3.70256 } },
	{ name: 'Ceuta', offset: 1, pos: { lat: 35.8883, log: -5.3162 } },
	{ name: 'Canary', offset: 0, pos: { lat: 28.1248, log: -15.43 } }
	]
}

const result = exp.eval('5*(7+9)==(5*7+5*9)')
console.log(result)
// Output: true

// use context
exp.eval('toNumber(phoneCode) <= 30', context)
// false

// template
exp.eval('`${name} belongs to ${region}`', context)
// 'Spain belongs to Europe'

exp.eval('timezones.filter(p => substring(p.name,0,1)=="C")', context)
// ['{"name":"Ceuta","offset":1,"pos":{"lat":35.8883,"log":-5.3162}}'
// ,'{"name":"Canary","offset":0,"pos":{"lat":28.1248,"log":-15.43}}']

exp.eval('timezones.filter(p => p.offset == 1).sort(p => p.pos.lat).name', context)
// ['Ceuta','Madrid']

exp.eval('stringify(timezones.first(p => p.name == "Madrid").pos)', context)
// '{"lat":40.4165,"log":-3.70256}'

exp.eval('timezones.filter(p => p.pos.lat > 30 && p.pos.log > -4).pos.lat', context)
// [40.4165]

exp.eval('sort(timezones.name)', context)
// ['Canary','Ceuta','Madrid']

exp.eval('timezones[0].name', context)
// 'Madrid'

exp.eval('round(timezones.first(p=> p.name =="Madrid").pos.lat - timezones.first(p=> p.name =="Ceuta").pos.lat,2)', context)
// 4.55

exp.eval('timezones.each(p => p.pos={lat:round(p.pos.lat,2),log:round(p.pos.log,2)}).map(p=> stringify(p))', context)
// ['{"name":"Madrid","offset":1,"pos":{"lat":40.4,"log":-3.7}}'
// ,'{"name":"Ceuta","offset":1,"pos":{"lat":35.9,"log":-5.3}}'
// ,'{"name":"Canary","offset":0,"pos":{"lat":28.1,"log":-15.45}}']

exp.eval(`
list = [1, 2, 3, 4, 5, 6, 7, 8, 9];
total = 0;
for (i = 0; i < list.length(); i += 1) {
	total += list[i];
}
`, context)
console.log(context.total)
// 45

exp.eval(`
while (p=timezones.pop()) {
	console(p);
}
`, context)
// outputs:
//         {"name":"Canary","offset":0,"pos":{"lat":28.1,"log":-15.45}}
//         {"name":"Ceuta","offset":1,"pos":{"lat":35.9,"log":-5.3}}
//         {"name":"Madrid","offset":1,"pos":{"lat":40.4,"log":-3.7}}

Documentation

• Arithmetic
• Comparison
• Logical
• Bitwise
• Numeric
• String
• DateTime
• Nullable
• Conversion
• Assignment
• Array
• Access
• Arrow
• Group
• Sets
• Control flows
• Extend
• Metadata