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The JavaScript JSON Cookbook

The JavaScript JSON Cookbook

By : Ray Rischpater, Brian Ritchie
1 (2)
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The JavaScript JSON Cookbook

The JavaScript JSON Cookbook

1 (2)
By: Ray Rischpater, Brian Ritchie

Overview of this book

If you're writing applications that move structured data from one place to another, this book is for you. This is especially true if you've been using XML to do the job because it's entirely possible that you could do much of the same work with less code and less data overhead in JSON. While the book's chapters make some distinction between the client and server sides of an application, it doesn't matter if you're a frontend, backend, or full-stack developer. The principles behind using JSON apply to both the client and the server, and in fact, developers who understand both sides of the equation generally craft the best applications.
Table of Contents (12 chapters)
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11
Index

Using JSONPath scripting to construct more complicated queries


Sometimes, what you really want to do is query all items that meet a certain criteria, such as those exceed a particular threshold. JSONPath provides the ?() predicate, which lets you execute simple comparison scripts of individual fields in your JSONPath.

How to do it…

Here's an example that queries all books costing less than 10 currency units:

$.store.book[?(@.price < 10)].title

How it works…

The query begins by specifying all book items in the store; the ?() predicate then selects each item in that category using the @ selector to obtain the value of the current item, and then selects prices less than 10. The resulting items have their title field extracted. This query yields the following results:

[ 
    "Sayings of the Century",
    "Moby Dick"
]

Queries like this don't work with all implementations of JSONPath. Checking the JSONPath Expression tester at http://jsonpath.curiousconcept.com/, I found that it worked using the...

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