when-condition

Developed by Flipbyte

Check conditional statements and return true/false

Installation

npm i @flipbyte/when-condition

Usage

Define your conditionals using an array with logical rule ('and' or 'or') as the first element followed by an array of comparison conditions.

General representation of a logical rule is as follows:

['{your logical rule}', [{your comparison rule 1}], [{your comparison rule 2}], ...]

Comparison rule is an array with 3 elements:

• The comparison rule.
• The key of the object whose value needs to be compared with a condition.
• The comparison value.

General representation of a comparison rule is as follows:

['{comparison rule}', '{key}', '{comparison value}']

Example

Consider an object as follows:

let data = {
    a: 1,
    b: 2,
    c: {
        d: 'string',
        e: [{
            f: 1,
            g: 2
        }]
    }
}

Single rule

To simply check one rule (say) data.a = 1

let rule = ['is', 'a', 1]

or

Check whether data.c.e[0].f = 1

let rule = ['is', 'c.e[0]`.f', 1]

Rules with multiple comparisons

Check whether both data.a = 1 and data.b = 2

let rule = ['and', ['is', 'a', 1], ['is', 'b', 2]]

Check whether either data.a = 1 or data.b = 2

let rule = ['or', ['is', 'a', 1], ['is', 'b', 2]]

Complex rules

Check whether (data.a = 1 and data.b = 2) or (data.b = 2 and data.c.d != 'string')

let rule = ['or', ['and', ['is', 'a', 1], ['is', 'b', 2]], ['and', ['is', 'b', 2], ['is', 'c.d', 'string']]]

Evaluating rules

import when from 'when-condition'

when(rule, data) // => returns true or false

Rules using callback

You can also pass a callback function to check the data. Which will be resolved to a promise. It can either be a plain function or a promise

when(function(data) {
    return data.a !== data.b
}, data).then((result) => {
    //...handle your result
})

Logical rules

There are 2 types of logical rules:

• and - checks whether all the conditions evaluate to true.
• or - checks whether atleast one condition evaluates to true.
• not - returns the opposite of the evaluated comparison rule. This logical rule takes only one comparison rule.

Comparison rules

Following are the available comparison rules:

• is - returns true if the object value strictly matches the comparison value.
• isOfType - returns true if the object value matches the specified type (Ex: string, undefined, etc.).
• anyOf - returns true if at least one of the comparison values matches the object key value. The comparison value needs to be an array.
• allOf - returns true if all the object key value matches the comparison values. The comparison value needs to be an array.
• gt - returns true if the object key value is greater than the comparison value
• gte - returns true if the object key value is greater than or equal to the comparison value
• lt - returns true if the object key value is lesser than the comparison value
• lte - returns true if the object key value is lesser than or equal to the comparison value

License

The MIT License (MIT)