Setting application/json as the data during the dragstart in HTML5 DND - javascript

I observed the setting the JSON data in HTML5DND will be converted into string. Are there any alternatives and best practices for passing JSON Data other than stringifying.
// During drag enter
event.dataTransfer.setData('application/json', {
id: 1
});
// During Drop data is printing as object
let data = event.dataTransfer.getData('application/json');
// printing [object Object]

There is no alternative for DataTransfer.setData() because its data (second) argument is a DOMString.
There is an alternative to DataTransfer--DataTransferItem; however, using it will involve stringifying the object (to pack that into a Blob of mimetype JSON).

In case my other answer does not answer your question, try dragging/dropping the object avatars into the textarea.
const object_1 = {id: 1}
const object_2 = {id: 2}
const p_1 = document.body.appendChild(document.createElement("p"))
const p_2 = document.body.appendChild(document.createElement("p"))
p_1.innerText = "object_1"
p_1.draggable = true
p_2.innerText = "object_2"
p_2.draggable = true
p_1.ondragstart = function () {
event.dataTransfer.setData("text", "object_1")
}
p_2.ondragstart = function () {
event.dataTransfer.setData("text", "object_2")
}
const textarea = document.body.appendChild(document.createElement("textarea"))
textarea.ondrop = function() {
event.preventDefault()
this.innerText = eval(event.dataTransfer.getData("text")).id
}

Related

Split a Javascript string by comma, but ignore commas that would be inside a string [duplicate]

My CSV data looks like this:
heading1,heading2,heading3,heading4,heading5
value1_1,value2_1,value3_1,value4_1,value5_1
value1_2,value2_2,value3_2,value4_2,value5_2
...
How do you read this data and convert to an array like this using JavaScript?:
[
heading1: value1_1,
heading2: value2_1,
heading3: value3_1,
heading4: value4_1
heading5: value5_1
],[
heading1: value1_2,
heading2: value2_2,
heading3: value3_2,
heading4: value4_2,
heading5: value5_2
]
....
I've tried this code but no luck!:
<script type="text/javascript">
var allText =[];
var allTextLines = [];
var Lines = [];
var txtFile = new XMLHttpRequest();
txtFile.open("GET", "file://d:/data.txt", true);
txtFile.onreadystatechange = function()
{
allText = txtFile.responseText;
allTextLines = allText.split(/\r\n|\n/);
};
document.write(allTextLines);
document.write(allText);
document.write(txtFile);
</script>
No need to write your own...
The jQuery-CSV library has a function called $.csv.toObjects(csv) that does the mapping automatically.
Note: The library is designed to handle any CSV data that is RFC 4180 compliant, including all of the nasty edge cases that most 'simple' solutions overlook.
Like #Blazemonger already stated, first you need to add line breaks to make the data valid CSV.
Using the following dataset:
heading1,heading2,heading3,heading4,heading5
value1_1,value2_1,value3_1,value4_1,value5_1
value1_2,value2_2,value3_2,value4_2,value5_2
Use the code:
var data = $.csv.toObjects(csv):
The output saved in 'data' will be:
[
{ heading1:"value1_1",heading2:"value2_1",heading3:"value3_1",heading4:"value4_1",heading5:"value5_1" }
{ heading1:"value1_2",heading2:"value2_2",heading3:"value3_2",heading4:"value4_2",heading5:"value5_2" }
]
Note: Technically, the way you wrote the key-value mapping is invalid JavaScript. The objects containing the key-value pairs should be wrapped in brackets.
If you want to try it out for yourself, I suggest you take a look at the Basic Usage Demonstration under the 'toObjects()' tab.
Disclaimer: I'm the original author of jQuery-CSV.
Update:
Edited to use the dataset that the op provided and included a link to the demo where the data can be tested for validity.
Update2:
Due to the shuttering of Google Code. jquery-csv has moved to GitHub
NOTE: I concocted this solution before I was reminded about all the "special cases" that can occur in a valid CSV file, like escaped quotes. I'm leaving my answer for those who want something quick and dirty, but I recommend Evan's answer for accuracy.
This code will work when your data.txt file is one long string of comma-separated entries, with no newlines:
data.txt:
heading1,heading2,heading3,heading4,heading5,value1_1,...,value5_2
javascript:
$(document).ready(function() {
$.ajax({
type: "GET",
url: "data.txt",
dataType: "text",
success: function(data) {processData(data);}
});
});
function processData(allText) {
var record_num = 5; // or however many elements there are in each row
var allTextLines = allText.split(/\r\n|\n/);
var entries = allTextLines[0].split(',');
var lines = [];
var headings = entries.splice(0,record_num);
while (entries.length>0) {
var tarr = [];
for (var j=0; j<record_num; j++) {
tarr.push(headings[j]+":"+entries.shift());
}
lines.push(tarr);
}
// alert(lines);
}
The following code will work on a "true" CSV file with linebreaks between each set of records:
data.txt:
heading1,heading2,heading3,heading4,heading5
value1_1,value2_1,value3_1,value4_1,value5_1
value1_2,value2_2,value3_2,value4_2,value5_2
javascript:
$(document).ready(function() {
$.ajax({
type: "GET",
url: "data.txt",
dataType: "text",
success: function(data) {processData(data);}
});
});
function processData(allText) {
var allTextLines = allText.split(/\r\n|\n/);
var headers = allTextLines[0].split(',');
var lines = [];
for (var i=1; i<allTextLines.length; i++) {
var data = allTextLines[i].split(',');
if (data.length == headers.length) {
var tarr = [];
for (var j=0; j<headers.length; j++) {
tarr.push(headers[j]+":"+data[j]);
}
lines.push(tarr);
}
}
// alert(lines);
}
http://jsfiddle.net/mblase75/dcqxr/
Don't split on commas -- it won't work for most CSV files, and this question has wayyyy too many views for the asker's kind of input data to apply to everyone. Parsing CSV is kind of scary since there's no truly official standard, and lots of delimited text writers don't consider edge cases.
This question is old, but I believe there's a better solution now that Papa Parse is available. It's a library I wrote, with help from contributors, that parses CSV text or files. It's the only JS library I know of that supports files gigabytes in size. It also handles malformed input gracefully.
1 GB file parsed in 1 minute:
(Update: With Papa Parse 4, the same file took only about 30 seconds in Firefox. Papa Parse 4 is now the fastest known CSV parser for the browser.)
Parsing text is very easy:
var data = Papa.parse(csvString);
Parsing files is also easy:
Papa.parse(file, {
complete: function(results) {
console.log(results);
}
});
Streaming files is similar (here's an example that streams a remote file):
Papa.parse("http://example.com/bigfoo.csv", {
download: true,
step: function(row) {
console.log("Row:", row.data);
},
complete: function() {
console.log("All done!");
}
});
If your web page locks up during parsing, Papa can use web workers to keep your web site reactive.
Papa can auto-detect delimiters and match values up with header columns, if a header row is present. It can also turn numeric values into actual number types. It appropriately parses line breaks and quotes and other weird situations, and even handles malformed input as robustly as possible. I've drawn on inspiration from existing libraries to make Papa, so props to other JS implementations.
I am using d3.js for parsing csv file. Very easy to use.
Here is the docs.
Steps:
npm install d3-request
Using Es6;
import { csv } from 'd3-request';
import url from 'path/to/data.csv';
csv(url, function(err, data) {
console.log(data);
})
Please see docs for more.
Update -
d3-request is deprecated. you can use d3-fetch
Here's a JavaScript function that parses CSV data, accounting for commas found inside quotes.
// Parse a CSV row, accounting for commas inside quotes
function parse(row){
var insideQuote = false,
entries = [],
entry = [];
row.split('').forEach(function (character) {
if(character === '"') {
insideQuote = !insideQuote;
} else {
if(character == "," && !insideQuote) {
entries.push(entry.join(''));
entry = [];
} else {
entry.push(character);
}
}
});
entries.push(entry.join(''));
return entries;
}
Example use of the function to parse a CSV file that looks like this:
"foo, the column",bar
2,3
"4, the value",5
into arrays:
// csv could contain the content read from a csv file
var csv = '"foo, the column",bar\n2,3\n"4, the value",5',
// Split the input into lines
lines = csv.split('\n'),
// Extract column names from the first line
columnNamesLine = lines[0],
columnNames = parse(columnNamesLine),
// Extract data from subsequent lines
dataLines = lines.slice(1),
data = dataLines.map(parse);
// Prints ["foo, the column","bar"]
console.log(JSON.stringify(columnNames));
// Prints [["2","3"],["4, the value","5"]]
console.log(JSON.stringify(data));
Here's how you can transform the data into objects, like D3's csv parser (which is a solid third party solution):
var dataObjects = data.map(function (arr) {
var dataObject = {};
columnNames.forEach(function(columnName, i){
dataObject[columnName] = arr[i];
});
return dataObject;
});
// Prints [{"foo":"2","bar":"3"},{"foo":"4","bar":"5"}]
console.log(JSON.stringify(dataObjects));
Here's a working fiddle of this code.
Enjoy! --Curran
You can use PapaParse to help.
https://www.papaparse.com/
Here is a CodePen.
https://codepen.io/sandro-wiggers/pen/VxrxNJ
Papa.parse(e, {
header:true,
before: function(file, inputElem){ console.log('Attempting to Parse...')},
error: function(err, file, inputElem, reason){ console.log(err); },
complete: function(results, file){ $.PAYLOAD = results; }
});
If you want to solve this without using Ajax, use the FileReader() Web API.
Example implementation:
Select .csv file
See output
function readSingleFile(e) {
var file = e.target.files[0];
if (!file) {
return;
}
var reader = new FileReader();
reader.onload = function(e) {
var contents = e.target.result;
displayContents(contents);
displayParsed(contents);
};
reader.readAsText(file);
}
function displayContents(contents) {
var element = document.getElementById('file-content');
element.textContent = contents;
}
function displayParsed(contents) {
const element = document.getElementById('file-parsed');
const json = contents.split(',');
element.textContent = JSON.stringify(json);
}
document.getElementById('file-input').addEventListener('change', readSingleFile, false);
<input type="file" id="file-input" />
<h3>Raw contents of the file:</h3>
<pre id="file-content">No data yet.</pre>
<h3>Parsed file contents:</h3>
<pre id="file-parsed">No data yet.</pre>
function CSVParse(csvFile)
{
this.rows = [];
var fieldRegEx = new RegExp('(?:\s*"((?:""|[^"])*)"\s*|\s*((?:""|[^",\r\n])*(?:""|[^"\s,\r\n]))?\s*)(,|[\r\n]+|$)', "g");
var row = [];
var currMatch = null;
while (currMatch = fieldRegEx.exec(this.csvFile))
{
row.push([currMatch[1], currMatch[2]].join('')); // concatenate with potential nulls
if (currMatch[3] != ',')
{
this.rows.push(row);
row = [];
}
if (currMatch[3].length == 0)
break;
}
}
I like to have the regex do as much as possible. This regex treats all items as either quoted or unquoted, followed by either a column delimiter, or a row delimiter. Or the end of text.
Which is why that last condition -- without it it would be an infinite loop since the pattern can match a zero length field (totally valid in csv). But since $ is a zero length assertion, it won't progress to a non match and end the loop.
And FYI, I had to make the second alternative exclude quotes surrounding the value; seems like it was executing before the first alternative on my javascript engine and considering the quotes as part of the unquoted value. I won't ask -- just got it to work.
Per the accepted answer,
I got this to work by changing the 1 to a 0 here:
for (var i=1; i<allTextLines.length; i++) {
changed to
for (var i=0; i<allTextLines.length; i++) {
It will compute the a file with one continuous line as having an allTextLines.length of 1. So if the loop starts at 1 and runs as long as it's less than 1, it never runs. Hence the blank alert box.
$(function() {
$("#upload").bind("click", function() {
var regex = /^([a-zA-Z0-9\s_\\.\-:])+(.csv|.xlsx)$/;
if (regex.test($("#fileUpload").val().toLowerCase())) {
if (typeof(FileReader) != "undefined") {
var reader = new FileReader();
reader.onload = function(e) {
var customers = new Array();
var rows = e.target.result.split("\r\n");
for (var i = 0; i < rows.length - 1; i++) {
var cells = rows[i].split(",");
if (cells[0] == "" || cells[0] == undefined) {
var s = customers[customers.length - 1];
s.Ord.push(cells[2]);
} else {
var dt = customers.find(x => x.Number === cells[0]);
if (dt == undefined) {
if (cells.length > 1) {
var customer = {};
customer.Number = cells[0];
customer.Name = cells[1];
customer.Ord = new Array();
customer.Ord.push(cells[2]);
customer.Point_ID = cells[3];
customer.Point_Name = cells[4];
customer.Point_Type = cells[5];
customer.Set_ORD = cells[6];
customers.push(customer);
}
} else {
var dtt = dt;
dtt.Ord.push(cells[2]);
}
}
}
Actually you can use a light-weight library called any-text.
install dependencies
npm i -D any-text
use custom command to read files
var reader = require('any-text');
reader.getText(`path-to-file`).then(function (data) {
console.log(data);
});
or use async-await :
var reader = require('any-text');
const chai = require('chai');
const expect = chai.expect;
describe('file reader checks', () => {
it('check csv file content', async () => {
expect(
await reader.getText(`${process.cwd()}/test/files/dummy.csv`)
).to.contains('Lorem ipsum');
});
});
This is an old question and in 2022 there are many ways to achieve this. First, I think D3 is one of the best alternatives for data manipulation. It's open sourced and free to use, but also it's modular so we can import just the fetch module.
Here is a basic example. We will use the legacy mode so I will import the entire D3 library. Now, let's call d3.csv function and it's done. This function internally calls the fetch method therefore, it can open dataURL, url, files, blob, and so on.
const fileInput = document.getElementById('csv')
const outElement = document.getElementById('out')
const previewCSVData = async dataurl => {
const d = await d3.csv(dataurl)
console.log({
d
})
outElement.textContent = d.columns
}
const readFile = e => {
const file = fileInput.files[0]
const reader = new FileReader()
reader.onload = () => {
const dataUrl = reader.result;
previewCSVData(dataUrl)
}
reader.readAsDataURL(file)
}
fileInput.onchange = readFile
<script type="text/javascript" src="https://unpkg.com/d3#7.6.1/dist/d3.min.js"></script>
<div>
<p>Select local CSV File:</p>
<input id="csv" type="file" accept=".csv">
</div>
<pre id="out"><p>File headers will appear here</p></pre>
If we don't want to use any library and we just want to use pain JavaScrip (Vanilla JS) and we managed to get the text content of a file as data and we don't want to use d3 we can implement a simple function that will split the data into a text array then we will extract the first line and split into a headers array and the rest of the text will be the lines we will process. After, we map each line and extract its values and create a row object from an array created from mapping each header to its correspondent value from values[index].
NOTE:
We also we going to use a little trick array objects in JavaScript can also have attributes. Yes so we will define an attribute rows.headers and assign the headers to it.
const data = `heading_1,heading_2,heading_3,heading_4,heading_5
value_1_1,value_2_1,value_3_1,value_4_1,value_5_1
value_1_2,value_2_2,value_3_2,value_4_2,value_5_2
value_1_3,value_2_3,value_3_3,value_4_3,value_5_3`
const csvParser = data => {
const text = data.split(/\r\n|\n/)
const [first, ...lines] = text
const headers = first.split(',')
const rows = []
rows.headers = headers
lines.map(line => {
const values = line.split(',')
const row = Object.fromEntries(headers.map((header, i) => [header, values[i]]))
rows.push(row)
})
return rows
}
const d = csvParser(data)
// Accessing to the theaders attribute
const headers = d.headers
console.log({headers})
console.log({d})
Finally, let's implement a vanilla JS file loader using fetch and parsing the csv file.
const fetchFile = async dataURL => {
return await fetch(dataURL).then(response => response.text())
}
const csvParser = data => {
const text = data.split(/\r\n|\n/)
const [first, ...lines] = text
const headers = first.split(',')
const rows = []
rows.headers = headers
lines.map(line => {
const values = line.split(',')
const row = Object.fromEntries(headers.map((header, i) => [header, values[i]]))
rows.push(row)
})
return rows
}
const fileInput = document.getElementById('csv')
const outElement = document.getElementById('out')
const previewCSVData = async dataURL => {
const data = await fetchFile(dataURL)
const d = csvParser(data)
console.log({ d })
outElement.textContent = d.headers
}
const readFile = e => {
const file = fileInput.files[0]
const reader = new FileReader()
reader.onload = () => {
const dataURL = reader.result;
previewCSVData(dataURL)
}
reader.readAsDataURL(file)
}
fileInput.onchange = readFile
<script type="text/javascript" src="https://unpkg.com/d3#7.6.1/dist/d3.min.js"></script>
<div>
<p>Select local CSV File:</p>
<input id="csv" type="file" accept=".csv">
</div>
<pre id="out"><p>File contents will appear here</p></pre>
I used this file to test it
Here is another way to read an external CSV into Javascript (using jQuery).
It's a little bit more long winded, but I feel by reading the data into arrays you can exactly follow the process and makes for easy troubleshooting.
Might help someone else.
The data file example:
Time,data1,data2,data2
08/11/2015 07:30:16,602,0.009,321
And here is the code:
$(document).ready(function() {
// AJAX in the data file
$.ajax({
type: "GET",
url: "data.csv",
dataType: "text",
success: function(data) {processData(data);}
});
// Let's process the data from the data file
function processData(data) {
var lines = data.split(/\r\n|\n/);
//Set up the data arrays
var time = [];
var data1 = [];
var data2 = [];
var data3 = [];
var headings = lines[0].split(','); // Splice up the first row to get the headings
for (var j=1; j<lines.length; j++) {
var values = lines[j].split(','); // Split up the comma seperated values
// We read the key,1st, 2nd and 3rd rows
time.push(values[0]); // Read in as string
// Recommended to read in as float, since we'll be doing some operations on this later.
data1.push(parseFloat(values[1]));
data2.push(parseFloat(values[2]));
data3.push(parseFloat(values[3]));
}
// For display
var x= 0;
console.log(headings[0]+" : "+time[x]+headings[1]+" : "+data1[x]+headings[2]+" : "+data2[x]+headings[4]+" : "+data2[x]);
}
})
Hope this helps someone in the future!
A bit late but I hope it helps someone.
Some time ago even I faced a problem where the string data contained \n in between and while reading the file it used to read as different lines.
Eg.
"Harry\nPotter","21","Gryffindor"
While-Reading:
Harry
Potter,21,Gryffindor
I had used a library csvtojson in my angular project to solve this problem.
You can read the CSV file as a string using the following code and then pass that string to the csvtojson library and it will give you a list of JSON.
Sample Code:
const csv = require('csvtojson');
if (files && files.length > 0) {
const file: File = files.item(0);
const reader: FileReader = new FileReader();
reader.readAsText(file);
reader.onload = (e) => {
const csvs: string = reader.result as string;
csv({
output: "json",
noheader: false
}).fromString(csvs)
.preFileLine((fileLine, idx) => {
//Convert csv header row to lowercase before parse csv file to json
if (idx === 0) { return fileLine.toLowerCase() }
return fileLine;
})
.then((result) => {
// list of json in result
});
}
}
I use the jquery-csv to do this.
and I provide two examples as below
async function ReadFile(file) {
return await file.text()
}
function removeExtraSpace(stringData) {
stringData = stringData.replace(/,( *)/gm, ",") // remove extra space
stringData = stringData.replace(/^ *| *$/gm, "") // remove space on the beginning and end.
return stringData
}
function simpleTest() {
let data = `Name, Age, msg
foo, 25, hello world
bar, 18, "!! 🐬 !!"
`
data = removeExtraSpace(data)
console.log(data)
const options = {
separator: ",", // default "," . (You may want to Tab "\t" or somethings.
delimiter: '"', // default "
headers: true // default true
}
// const myObj = $.csv.toObjects(data, options)
const myObj = $.csv.toObjects(data) // If you want to use default options, then you can omit them.
console.log(myObj)
}
window.onload = () => {
const inputFile = document.getElementById("uploadFile")
inputFile.onchange = () => {
const inputValue = inputFile.value
if (inputValue === "") {
return
}
const selectedFile = document.getElementById('uploadFile').files[0]
const promise = new Promise(resolve => {
const fileContent = ReadFile(selectedFile)
resolve(fileContent)
})
promise.then(fileContent => {
// Use promise to wait for the file reading to finish.
console.log(fileContent)
fileContent = removeExtraSpace(fileContent)
const myObj = $.csv.toObjects(fileContent)
console.log(myObj)
})
}
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery-csv/1.0.11/jquery.csv.min.js"></script>
<label for="uploadFile">Demo 1</label>
<input type="file" id="uploadFile" accept=".csv"/>
<button onclick="simpleTest()">Demo 2</button>
With this function csvToObjs you can transform data-entries from format CSV to an array of objects.
function csvToObjs(string) {
const lines = data.split(/\r\n|\n/);
let [headings, ...entries] = lines;
headings = headings.split(',');
const objs = [];
entries.map(entry=>{
obj = entry.split(',');
objs.push(Object.fromEntries(headings.map((head, i)=>[head, obj[i]])));
})
return objs;
}
data = `heading1,heading2,heading3,heading4,heading5
value1_1,value2_1,value3_1,value4_1,value5_1
value1_2,value2_2,value3_2,value4_2,value5_2`
console.log(csvToObjs(data));

localStorage array.push

Could someone tell me how to push elements into an array in localStorage?
My code:
(localStorage.getItem('projects') === null) ? localStorage.setItem('projects', ['proj1', 'proj2', 'proj3']) : '';
var ItemGet = localStorage.getItem('projects');
function CreateObject() {
console.log(ItemGet);
var Serializable = JSON.parse(ItemGet);
Serializable.push('proj4');
console.log(ItemGet);
}
<button onclick="CreateObject()">Add Object</button>
General approach:
let old_data = JSON.parse(localStorage.getItem('projects'))
let new_data = old_data.push(some_new_data)
localStorage.setItem('projects',JSON.stringify(new_data))
I would do the following assuming that your data is not a multiDimensional array.
(localStorage.getItem('projects') === null) ? localStorage.setItem('projects',
JSON.stringify(['proj1', 'proj2', 'proj3'])) : '';
var ItemGet = localStorage.getItem('projects');
function CreateObject() {
var Serializable = JSON.parse(ItemGet);
Serializable.push('proj4');
localStorage.setItem('projects',JSON.stringify(Serializable));
}
The problem you are hitting is that data stored in localStorage has to be a string. You'll have to parse/stringify before settting/getting anything from local storage. If you didn't want to work with strings, you may find something like IndexedDB API
const stuff = [ 1, 2, 3 ];
// Stringify it before setting it
localStorage.setItem('stuff', JSON.stringify(stuff));
// Parse it after getting it
JSON.parse(localStorage.getItem('stuff'));
Here is an example of using IndexedDB API from the docs
const dbName = "the_name";
var request = indexedDB.open(dbName, 2);
request.onerror = function(event) {
// Handle errors.
};
request.onupgradeneeded = function(event) {
var db = event.target.result;
// Create an objectStore to hold information about our customers. We're
// going to use "ssn" as our key path because it's guaranteed to be
// unique - or at least that's what I was told during the kickoff meeting.
var objectStore = db.createObjectStore("customers", { keyPath: "ssn" });
// Create an index to search customers by name. We may have duplicates
// so we can't use a unique index.
objectStore.createIndex("name", "name", { unique: false });
// Create an index to search customers by email. We want to ensure that
// no two customers have the same email, so use a unique index.
objectStore.createIndex("email", "email", { unique: true });
// Use transaction oncomplete to make sure the objectStore creation is
// finished before adding data into it.
objectStore.transaction.oncomplete = function(event) {
// Store values in the newly created objectStore.
var customerObjectStore = db.transaction("customers", "readwrite").objectStore("customers");
customerData.forEach(function(customer) {
customerObjectStore.add(customer);
});
};
};
There are also other solutions out there like PouchDB depending on your needs
Say for example you have an array. This is how you can store it in the local storage.
let my_array = [1, 2, 3, 4];
localStorage.setItem('local_val', JSON.stringify(my_array))
Now to push any data into the local storage array you have to override by the new data like bellow
let oldArray = JSON.parse(localStorage.getItem('local_val'))
oldArray.push(1000)
localStorage.setItem('local_val', JSON.stringify(oldArray))

Update ONLY some fields of an object in IndexedDB

For example:
object1(1) = {
name: 'Rhodok Sergeant',
speciality: 'Hand to hand battle'
}
then I want to update only the speciality field, into:
object1(1) = {
name: 'Rhodok Sergeant',
speciality: 'Long range battle'
}
Thank you.
This is possible using following steps -
fetch the item first using idbcursor
update that item
call cursor.update to store updated data in indexedb.
An example code is -
const transaction = db.transaction(['rushAlbumList'], 'readwrite');
const objectStore = transaction.objectStore('rushAlbumList');
objectStore.openCursor().onsuccess = function(event) {
const cursor = event.target.result;
if (cursor) {
if (cursor.value.albumTitle === 'A farewell to kings') {
const updateData = cursor.value;
updateData.year = 2050;
const request = cursor.update(updateData);
request.onsuccess = function() {
console.log('data updated');
};
};
cursor.continue();
}
};
Check out this link for more info - https://developer.mozilla.org/en-US/docs/Web/API/IDBCursor/update
Note:- In above code, i am looping through all records which is not efficient in case you want to fetch the particular record based on some condition. So you can use idbKeyRange or some other idb query alternative for this.
you cannot do partial updates, you can only overwrite an entire object
read the object in from memory, change it, and then write it back

Get value from Request URL response data

Requested URL sent - https://www.example.com/detail.guest.html?ppc=FDE466920006DCEFA697BF982FC9C87C5B257ECB2230CBF4D6D6CA740C7B894D5795F70DED928ED3B00C1F3F77DF974DFD73882DEBDD7EC063B37DEB24CF655528FD911109C57961AE314C612772AADFD2E193D572E6F6C8E249A6DAA
Get below response data correctly as expected by 3rd party.
BookersID=250100000002;BookersTitle=Mr;BookersFirstName=test1;BookersLastName=test2
I want to extract "BookersID", "BookersTitle", "BookersFirstName", "BookersLastName" separately and display this value in input field.
JS:
var bookerID = data[0].BookersID;
var bookerTitle = data[0].BookersTitle;
var bookerFname = data[0].BookersFirstName;
var bookerLname = data[0].BookersLastName;
console.log("BookersID", bookerID);
console.log("BookersTitle", bookerTitle);
But getting error in display value.
Please let me know how to get the value in console log?
Thanks
First you need to get data from your xhr request. To do that you need to add callback function. (More info in jQuery.get() documentation)
$.get( endpoint, function( data ) { // add callback to handle response
// ... parse data here
});
As I understand you need to parse data. It could be done by using String.prototype.split method and simple mapping.
console.log(data) // BookersID=250100000002;BookersTitle=Mr;BookersFirstName=test1;BookersLastName=test2
var parsed = data.split(';').map(part => ({ name: part.split('=')[0], value: part.split('=')[1] }));
console.log(parsed);
Output:
[
{name: "BookersID", value: "250100000002"},
{name: "BookersTitle", value: "Mr"},
{name: "BookersFirstName", value: "test1"},
{name: "BookersLastName", value: "test2"}
]
If you want to get data as an object:
var parsedObject = parsed.reduce(
(obj, item) => Object.assign(obj, {[item.name]: item.value}) ,{});
// {BookersID: "250100000002", BookersTitle: "Mr", BookersFirstName: "test1", BookersLastName: "test2"}
If you getting the same response you need to write a utility function to convert the same into an object
function _convert(responseString) {
var _obj = {};
responseString.split(";").forEach(function(pair){
var _pairArr = pair.split("=");
_obj[_pairArr[0]] = _pairArr[1];
});
reuturn _obj;
}
var responseString = "BookersID=250100000002;BookersTitle=Mr;BookersFirstName=test1;BookersLastName=test2";
var obj = _convert(responseString);
obj['BookersID']; // 250100000002
// or
obj.BookersID; // 250100000002
Note: This will only work if your response has exactly the same format as you have mentioned.
var str = 'BookersID=250100000002;BookersTitle=Mr;BookersFirstName=test1;BookersLastName=test2';
var data = {};
var parsed = str.split(';').map(part => { let x = part.split("="); data[x[0]] = x[1]; console.log(x) });
console.log(data)
Output:
{BookersID: "250100000002", BookersTitle: "Mr", BookersFirstName: "test1", BookersLastName: "test2"}
You could use .reduce() and .split() to create your string into an object, which can then have its properties accessed
const data = "BookersID=250100000002;BookersTitle=Mr;BookersFirstName=test1;BookersLastName=test2";
const dataObj = data.split(';').reduce((acc, kvp) =>
({
...acc,
...(([key, value]) => ({[key]: value}))(kvp.split('='))
}), {});
console.log(dataObj);
// access properties:
console.log(dataObj.BookersID);

using json objects in URLSearchParams

Is it possible to somehow append json objects onto a URLSearchParams object?
So instead of:
urlSearchParams.append('search', 'person');
it's:
urlSearchParams.append({search: "person"});
My answer courtesy of Darshak Gajjar's answer
Can use json objects via this way:
let test_this = [{"search": "person"}, { search: "another person"}];
var json = JSON.stringify(test_this);
urlSearchParams.append("myobj", json);
return this.http.post(this.post_url, urlSearchParams, options) //options being your own RequestOptions
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign
Something like this might work urlSearchParams = Object.assign(urlSearchParams, {search: "person"});
EDIT: Alternate solution using vanilla javascript. Also, I thought URLSearchParams was just a normal js object, but in fact you have to use get, set and append to access properties.
var params = new URLSearchParams("a=apple&b=balloon");
var parametersToAdd = {c: "car", d: "duck"};
for(key in parametersToAdd)
params.append(key, parametersToAdd[key]);
console.log(params.get('c'));
console.log(params.get('d'));
EDIT bis:
.append() supports to re-use the same key/parameter name, while .set() would have overwritten a previous value.
May be using below code you can pass entire json object in URL Search param
var json = JSON.stringify(myObj);
this.http.get('url'+'?myobj='+encodeURIComponent(json))
There's no API for that. You just need to enumerate over the properties and append them manually, for example using the following function:
function appendParams(params: URLSearchParams, obj: any) {
for (let key in obj) {
if (obj.hasOwnProperty(key)) {
params.append(key, obj[key])
}
}
}
appendParams(urlSearchParams, { search: 'person' });
Want to share my answer for Angular2 with the option of sending an Array
This is how I use this get function:
this.get('/api/database', {
'age': [1,2,3,4]
})
And the service is something like:
get(url, _params = {}) {
let params = this._processParams(_params);
return this.http.get(url, params).toPromise();
}
_processParams(obj: any) {
/* Convert this
{ age: [1,2,3] }
To:
param.append('age', 1);
param.append('age', 2);
param.append('age', 3);
*/
let params = new URLSearchParams();
for (let key in obj) {
for (let index in obj[key] ) {
params.append(key, obj[key][index]);
}
}
return {
search: params
};
}
Super simple answer/example:
// Create:
const params = new URLSearchParams({
a: 1,
b: 2
})
// OR
// const params = new URLSearchParams("a=1&b=2")
// Append
params.append('c', 'woohoo') // Note: if c param already exists in params, this will replace it (won't be adding new param if already exists, hence no duplications)
console.log(params.toString())
// Prints: 'a=1&b=2&c=woohoo'
Here is my approach. We have a simple requirement where the object is only a key value pair where the value might be a string or an array. We haven't found a use case for nested objects.
So let's say we want to convert this object into a query string or vice versa:
const input = {
ini: 'ini',
itu: 'itu',
ayo: ['desc', 'asc'],
}
Then we have two functions to parse & stringify:
function stringify(input) {
const params = new URLSearchParams();
for (const key in input) {
if (Array.isArray(input[key])) {
input[key].forEach(val => {
params.append(key + '[]', val)
})
} else {
params.append(key, input[key]);
}
}
return '?' + params.toString();
}
function parse(input) {
const payload = {};
const params = new URLSearchParams(input);
for(let [key, val] of params.entries()) {
if (key.endsWith('[]')) {
key = key.replace(/\[\]$/, '');
if (payload[key]) {
payload[key].push(val);
} else {
payload[key] = [val]
}
} else {
payload[key] = val;
}
}
return payload;
}
So the result should be "?ini=ini&itu=itu&ayo%5B%5D=desc&ayo%5B%5D=asc". This is similar to the array format that is found in this example.
Please note that this might not be battle tested, but for us we don't really have complicated object structure.
const url = new URL('/', location.origin);
console.log(url.href); // https://stackoverflow.com/
Object.entries({this:4,that:1}).forEach((item)=>{
// note .set replaces while .append will duplicate params
url.searchParams.append(...item);
});
console.log(url.href); // https://stackoverflow.com/?this=4&that=1

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