JSON Extension Functions

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Written by John DeVight on 24 Jun 2011 15:06

Download the source code here.

Overview

I do a lot of client side coding in my ASP.NET applications. The data that I work with is in JSON format. Since a deal with arrays of JSON objects, I extended the JSON class to include additional functions to work with arrays of JSON objects.

To ensure that I had a JSON object to work with, I downloaded the json2.js file from the following site: https://github.com/douglascrockford/JSON-js

How to use the Extension Functions

JSON.findArrayElement()

Description:
Get the first occurrence of the JSON element in the array.

Syntax:
JSON.findArrayElement(objJsonArray, elementName, elementValue);

Return Value:
element found in the array or null if not found.

Examples:

var sampleJsonArray = [{FirstName: 'William', LastName: 'Adama', Role: 'Commander'},
                                {FirstName: 'Lee', LastName: 'Adama', Role: 'Pilot'},
                                {FirstName: 'Kara', LastName: 'Thrace', Role: 'Pilot'}];

// Get the first occurrence of the JSON element where the FirstName is Lee.
var leeadama = JSON.findArrayElement(sampleJsonArray, 'FirstName', 'Lee');

JSON.findAllArrayElements()

Description:
Get all occurrences of the JSON element in the array.

Syntax:
JSON.findAllArrayElements(objJsonArray, elementName, elementValue);

Return Value:
array of elements found in the array. The array will be empty if no elements are found.

Examples:

var sampleJsonArray = [{FirstName: 'William', LastName: 'Adama', Role: 'Commander'},
                                {FirstName: 'Lee', LastName: 'Adama', Role: 'Pilot'},
                                {FirstName: 'Kara', LastName: 'Thrace', Role: 'Pilot'}];

// Get the all occurrences of the JSON element where the Role is Pilot.
var leeadama = JSON.findAllArrayElements(sampleJsonArray, 'Role', 'Pilot');

JSON.indexOfArrayElement()

Description:
Get the index of the first occurence of the JSON element in the array.

Syntax:
JSON.indexOfArrayElement(objJsonArray, elementName, elementValue);

Return Value:
index of the element found in the array or null if not found.

Examples:

var sampleJsonArray = [{FirstName: 'William', LastName: 'Adama', Role: 'Commander'},
                                {FirstName: 'Lee', LastName: 'Adama', Role: 'Pilot'},
                                {FirstName: 'Kara', LastName: 'Thrace', Role: 'Pilot'}];

// Get the index of the first occurence of the JSON element where the 'Role' is 'Commander'.
var idx = JSON.indexOfArrayElement(sampleJsonArray, 'Role', 'Commander');

JSON.removeArrayElement()

Description:
Remove the first occurence of the JSON element in the array.

Syntax:
JSON.removeArrayElement(objJsonArray, elementName, elementValue);

Return Value:
None

Examples:

var sampleJsonArray = [{FirstName: 'William', LastName: 'Adama', Role: 'Commander'},
                                {FirstName: 'Lee', LastName: 'Adama', Role: 'Pilot'},
                                {FirstName: 'Kara', LastName: 'Thrace', Role: 'Pilot'}];

// Remove the first occurence of the JSON element where the 'Role' is 'Commander'.
JSON.removeArrayElement(sampleJsonArray, 'Role', 'Commander');

JSON.removeArrayElementByIndex()

Description:
Remove the first occurence of the JSON element in the array using the zero based index passed in.

Syntax:
JSON.removeArrayElementByIndex(objJsonArray, idx);

Return Value:
None

Examples:

var sampleJsonArray = [{FirstName: 'William', LastName: 'Adama', Role: 'Commander'},
                                {FirstName: 'Lee', LastName: 'Adama', Role: 'Pilot'},
                                {FirstName: 'Kara', LastName: 'Thrace', Role: 'Pilot'}];

// Remove the second JSON element from the array.
JSON.removeArrayElement(sampleJsonArray, 1);

JSON.replaceArrayElement()

Description:
Replace a JSON element in the array with a new JSON element.

Syntax:
JSON.replaceArrayElement(objJsonArray, elementName, elementValue, newJsonElement);

Return Value:
index of the element replaced in the array or null if not found.

Examples:

var sampleJsonArray = [{FirstName: 'William', LastName: 'Adama', Role: 'Commander'},
                                {FirstName: 'Lee', LastName: 'Adama', Role: 'Pilot'},
                                {FirstName: 'Kara', LastName: 'Thrace', Role: 'Pilot'}];

// Replace Lee Adama with a new role of President.
JSON.removeArrayElement(sampleJsonArray, 'FirstName', 'Lee', 
    { FirstName: 'Lee', LastName: 'Adama', Role: 'President' });

JSON.sortArrayElements()

Description:
Sort the elements in the JSON array.

Syntax:
JSON.sortArrayElements(objJsonArray, elementName, reverse, [optional: primer]);

Return Value:
None

Examples:

var sampleJsonArray = [{FirstName: 'William', LastName: 'Adama', Role: 'Commander', Age: 50},
                                {FirstName: 'Lee', LastName: 'Adama', Role: 'Pilot', Age: 29},
                                {FirstName: 'Kara', LastName: 'Thrace', Role: 'Pilot', Age: 27}];

// Sort ascending by LastName.
var sortedJsonArray = JSON.sortArrayElements(sampleJsonArray, 'LastName', false);

// Sort descending by Age.
// The "primer" that is passed in converts the value to an integer before performing the comparison.
var sortedJsonArray = JSON.sortArrayElements(sampleJsonArray, 'Age', true, 
    function(a) { return parseInt(a); });

References

• Douglas Crockford on github

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