How to read a properties file in javascript from project directory?

I'm building a Chrome Packaged App. I want to put the script configuration if a config file in a resource directory and on startup want to read that by Javascript.

For example

  • Project
    • WebContent
      • index.html
      • manifest.json
      • main.js
      • resource
        • config.properties

Here I want main.js to load config.properties file in the beginning and get key-value pairs.

Have anyone done something like this?

Answers:

Answer

There is a super simple way to do this, along the lines of sowbug's answer, but which doesn't need any XHR or file reading.

Step 1. Create resource/config.js like so:

gOptions = {
  // This can have nested stuff, arrays, etc.
  color: 'red',
  size: 'big',
  enabled: true,
  count: 5
}

Step 2. Include this file in your index.html:

<!doctype html>
<head>
  <script src="resource/config.js"></script>
  ...

Step 3. Access your options directly from your main.js (or anywhere):

  ...
  if (gOptions.enabled) {
    for (var i = 0; i < gOptions.count; i++) {
      console.log(gOptions.color);
    }
  }
  ...
Answer

You can use messageResource.js, a simple javascript library created by me for loading properties file.

1) Include messageResource.js in your index.html.

<script src="messageResource.min.js"></script>    

2) You can get key-value pairs of config.properties from main.js using the following code.

// initialize messageResource.js  
messageResource.init({
  // path to directory containing config.properties
  filePath : 'resource'
});

// load config.properties file
messageResource.load('config', function(){ 
  // load file callback 

  // get value corresponding  to a key from config.properties  
  var value = messageResource.get('key', 'config');
}); 
Answer

I know this was accepted as answered a long time ago but there never was a true "as is" .properties answer. There was only don't use that and instead convert it to .js. Obviously that would be preferable but not always possible. If it's not possible, say in a Java application that also has JavaScript somewhere and the .properties file is very much used by Java and shared by the JavaScript to avoid duplication, then an actual .properties answer would be best.

If you are using ES6, React, Vue, Angular, etc. then you can import it. Let's say it's a list of URLs in a URL.properties file. There is no need to specify the path even in JavaScript but a unique name is required.

import URL from 'URL';

The syntax can be tricky for keys with dots in them, such as widgetAPI.dev. You can't simply invoke it as URL.widgetAPI.dev. Since the properties file (content) is an object once it gets to JavaScript so you can reference it like any Object key, such as:

console.log(URL['widgetAPI.dev'])

If you are not in ES6, jQuery has libraries and there is always the ubiquitous messageResource already mentioned.

Answer

Structure the file as JSON. Read it into a string using the File API or XHR. Then JSON.parse(string).

Answer

It is pretty simple with JSF, but you will have to modify the HTML file every time you need a new parameter to be read from JavaScript. My property file (config.properties) in project directory has the following parameter as a key value pair.

parameter.key=parameter.value

The property file name is configured in faces-config.xml

<application>
    <resource-bundle>
        <base-name>com.example.project.properties.config</base-name>
        <var>configuration</var>
    </resource-bundle>
</application>

Therefore, you can use a property value in a hidden input inside the HTML file.

<h:inputHidden id="parameter_key" value="#{configuration['parameter.key']}" />

And from JavaScript function, use the following line to read the parameter value.

var parameter_value = document.getElementById("parameter_key").value;

Enjoy your day..!!!

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