Reading Property Files In Javascript

11-05-2021
 |  [RAND-100] - Comments

  • The value is one of the property's attributes. Other attributes are: enumerable, configurable, and writable. These attributes define how the property can be accessed (is it readable?, is it writable?) In JavaScript, all attributes can be read, but only the value attribute can be changed (and only if the property is writable).
  • Reading properties file in javascript. Matt Thomassan. Ranch Hand Posts: 44. Posted 9 years ago. Hi Ranchers, I am facing a problem. In my web application, I have a properties file that has many name-value pairs. Read a property file to set variables using javascript More.
  • Begins reading from blob as a 'data:' url string. The result will be stored on this.result after the 'load' event fires.

Properties are the most important part of any JavaScript object.

Parse and Read Excel Files (xls/xlsx) With JavaScript. 33 thoughts on “Parse and Read Excel Files (xls/xlsx) With JavaScript” rob says: January 9, 2014 at 3:21 AM. Cannot read property ‘v’ of undefined and the program crashes. Is there a workaround for this? I'd like to set some variables in a javascript by reading a properties file. Specifically, I need to determine the environment, like what server etc, various javascripts are operating in. This will be done on the server side. If you link to an example properties file but only want to parse some of them, then you need to clarify that. In either case, I think you should import the linked properties file into your question so that we don't have to leave the site to determine the requirements. .properties is a file extension for files mainly used in Java related technologies to store the configurable parameters of an application. They can also be used for storing strings for Internationalization and localization; these are known as Property Resource Bundles.

JavaScript Properties

Properties are the values associated with a JavaScript object.

A JavaScript object is a collection of unordered properties.

Properties can usually be changed, added, and deleted, but some are read only.

Accessing JavaScript Properties

The syntax for accessing the property of an object is:

or

or

The expression must evaluate to a property name.

Example 1

person.firstname + ' is ' + person.age + ' years old.';

Javascript Read Write File

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Example 2

person['firstname'] + ' is ' + person['age'] + ' years old.';
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JavaScript for...in Loop

The JavaScript for...in statement loops through the properties of an object.

Syntax

for (variable in object) {
// code to be executed
}

The block of code inside of the for...in loop will be executed once for each property.

Looping through the properties of an object:

Example

var person = {fname:'John', lname:'Doe', age:25};
for (x in person) {
txt += person[x];
}
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Adding New Properties

You can add new properties to an existing object by simply giving it a value.

Assume that the person object already exists - you can then give it new properties:

Example

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Deleting Properties

The delete keyword deletes a property from an object:

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Reading property file using javascript

Example

var person = {firstName:'John', lastName:'Doe', age:50, eyeColor:'blue'};
delete person.age; // or delete person['age'];

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The delete keyword deletes both the value of the property and the property itself.

After deletion, the property cannot be used before it is added back again.

The delete operator is designed to be used on object properties. It has no effect on variables or functions.

The delete operator should not be used on predefined JavaScript object properties. It can crash your application.

Property Attributes

All properties have a name. In addition they also have a value.

The value is one of the property's attributes.

Other attributes are: enumerable, configurable, and writable.

These attributes define how the property can be accessed (is it readable?, is it writable?)

Reading Property File In Javascript

In JavaScript, all attributes can be read, but only the value attribute can be changed (and only if the property is writable).

( ECMAScript 5 has methods for both getting and setting all property attributes)

Prototype Properties

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JavaScript objects inherit the properties of their prototype.

Reading Property Files In Java

The delete keyword does not delete inherited properties, but if you delete a prototype property, it will affect all objects inherited from the prototype.