propertiesSync

NAME

propertiesSync - Synchronous parsing and manipulating .properties files

SYNOPSIS

const properties = require('propertiesSync');
let props = properties.readPropertiesSync('config.properties');

let aB = props.a.b;
let c = props.c;

let props2 = properties.readPropertiesSync('config2.properties');
properties.mergeProperties(props, props2);

DESCRIPTION

This module provides two functions:

• Read .properties files using Node.js' synchronous filesystem interface. Since the files are read synchronously, an application's configuration will be available immediately.

• Merge two objects, allowing configuration objects to be combined.

readPropertiesSync

module.readPropertiesSync(path): Object

Read a file identified by path, producing an object.

A properties file consists, roughly, of lines, each consisting of a key and a value. The result of reading a file is an object mapping keys to values. If the key is made up of segments joined by periods, the key is broken into sub-keys, i.e. namespaces, each mapping to a sub-object.

For example, the properties file:

a.b.c = 1
a.b.d = 0
a.e = 2

is read into the object structure:

{
  a: {
    b: {
      c: "1",
      d: "0",
    },
    e: "2",
  }
}

If the file does not exist, undefined is returned.

If the file contains conflicting structure, an error is thrown. An example of such conflicts:

a.b.c = 1
a.b = 2

In this example, a.b is both an object and the value "2".

mergeProperties

module.mergeProperties(target, source,...)

Recursively merge the source objects onto the target object. A target object must be specified and will be modified, and one or more source objects.

For example, given the two properties files:

a.b.c = 1
a.b.d = 2

x.y.z = "potato"
r = "elbow"

the result of merging the two objects will be:

{
  a: {
    b: {
      c: "1",
      d: "2",
    },
  },
  x: {
    z: "potato",
  },
  r: "elbow",
}

SYNTAX

A properties file consists of logical lines. Each logical line is made of:

• A comment, beginning with '#' and continuing until the end of the line. The comment character can be escaped by a backslash ("#") to include it in a key or value.

• A key/value pair consisting of a key ending at the first ':' or '=' character, followed by a value. Keys are broken at periods ('.'), to create namespaces.

Multiple physical lines can be combined into a single logical line by escaping the terminating newline with a backslash ('').

SEE ALSO

• Alternative project: node-properties.

• The .properties file format. (This module does not completely implement that format.)

• .properties at Wikipedia.