Javascript Generate Dynamic Key Values In An Object
12.12.2020 admin
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- Javascript Generate Dynamic Key Values In An Objective
- What Are Key Values
- Add Property To Javascript Object
- Javascript Generate Dynamic Key Values In An Object Examples
- Ten Key Values
- Key Values In Life
JSON is a format for storing and transporting data.
Syntax Object.keys(obj)Parameters obj The object of which the enumerable's own properties are to be returned. Return value. An array of strings that represent all the enumerable properties of the given object. Sep 24, 2019 Create an object property whose name should be the value of a given variable. ES6 has brought 'Computed property names' that helps in creating a new object with dynamic property names. The new object is created normally, the only difference being is that the dynamic value is to be put between square brackets.
To match the object returned in the last section, the key value will be the array index for each item. In the code example, we'll be using a for loop to enumerate over each item in the array. But, you can use any other method of looping over an array that you wish ( while, while/do, etc). Nov 19, 2019 Dynamically creating properties on objects using javascript. Properties on the Javascript object help set values that can be used within the object to manage and use the data. Let us look at how to create dynamic properties on Javascript There are 2 ways to do this. Looping through objects in JavaScript 20th Jun 2018. Once in a while, you may need to loop through Objects in JavaScript. The only way to do so before ES6 is with a for.in loop. The problem with a for.in loop is that it iterates through properties in the Prototype chain. When you loop through an object with the for.in loop, you need to check if the property belongs to the object.
JSON is often used when data is sent from a server to a web page.
What is JSON?
- Nov 12, 2019 Object.entries The Object.entries method was also introduced with ES2017, and the method returns an array of a given object’s own enumerable string-keyed property key, value pairs, in.
- If we’d like to apply them, then we can use Object.entries followed Object.fromEntries: Use Object.entries(obj) to get an array of key/value pairs from obj. Use array methods on that array, e.g. Use Object.fromEntries(array) on the resulting array to turn it back into an object.
- JSON stands for JavaScript Object Notation
- JSON is a lightweight data interchange format
- JSON is language independent *
- JSON is 'self-describing' and easy to understand
* The JSON syntax is derived from JavaScript object notation syntax, but the JSON format is text only. Code for reading and generating JSON data can be written in any programming language.
JSON Example
This JSON syntax defines an employees object: an array of 3 employee records (objects):
JSON Example
{
'employees':[
{'firstName':'John', 'lastName':'Doe'},
{'firstName':'Anna', 'lastName':'Smith'},
{'firstName':'Peter', 'lastName':'Jones'}
]
}
'employees':[
{'firstName':'John', 'lastName':'Doe'},
{'firstName':'Anna', 'lastName':'Smith'},
{'firstName':'Peter', 'lastName':'Jones'}
]
}
The JSON Format Evaluates to JavaScript Objects
The JSON format is syntactically identical to the code for creating JavaScript objects.
Because of this similarity, a JavaScript program can easily convert JSON data into native JavaScript objects.
JSON Syntax Rules
- Data is in name/value pairs
- Data is separated by commas
- Curly braces hold objects
- Square brackets hold arrays
JSON Data - A Name and a Value
JSON data is written as name/value pairs, just like JavaScript object properties.
A name/value pair consists of a field name (in double quotes), followed by a colon, followed by a value:
Javascript Generate Dynamic Key Values In An Objective
JSON names require double quotes. JavaScript names do not.
JSON Objects
JSON objects are written inside curly braces. /generate-certificate-from-private-key.html.
What Are Key Values
Just like in JavaScript, objects can contain multiple name/value pairs:
JSON Arrays
JSON arrays are written inside square brackets.
Just like in JavaScript, an array can contain objects:
Add Property To Javascript Object
'employees':[
{'firstName':'John', 'lastName':'Doe'},
{'firstName':'Anna', 'lastName':'Smith'},
{'firstName':'Peter', 'lastName':'Jones'}
]
{'firstName':'John', 'lastName':'Doe'},
{'firstName':'Anna', 'lastName':'Smith'},
{'firstName':'Peter', 'lastName':'Jones'}
]
In the example above, the object 'employees' is an array. It contains three objects.
Each object is a record of a person (with a first name and a last name).
Converting a JSON Text to a JavaScript Object
A common use of JSON is to read data from a web server, and display the data in a web page.
For simplicity, this can be demonstrated using a string as input.
First, create a JavaScript string containing JSON syntax:
var text = '{ 'employees' : [' +
'{ 'firstName':'John' , 'lastName':'Doe' },' +
'{ 'firstName':'Anna' , 'lastName':'Smith' },' +
'{ 'firstName':'Peter' , 'lastName':'Jones' } ]}';
'{ 'firstName':'John' , 'lastName':'Doe' },' +
'{ 'firstName':'Anna' , 'lastName':'Smith' },' +
'{ 'firstName':'Peter' , 'lastName':'Jones' } ]}';
Then, use the JavaScript built-in function JSON.parse() to convert the string into a JavaScript object:
Javascript Generate Dynamic Key Values In An Object Examples
Finally, use the new JavaScript object in your page:
Example
<p></p>
<script>
document.getElementById('demo').innerHTML =
obj.employees[1].firstName + ' ' + obj.employees[1].lastName;
</script>
Try it Yourself »<script>
document.getElementById('demo').innerHTML =
obj.employees[1].firstName + ' ' + obj.employees[1].lastName;
</script>
Ten Key Values
You can read more about JSON in our JSON tutorial.