pass EJS variable to be used in client side <script> [duplicate] - javascript

I am completely lost on this; I am using NodeJS to fetch a JSON and I need to pass the variable to my page and have JavaScript use the data.
app.get('/test', function(req, res) {
res.render('testPage', {
myVar: 'My Data'
});
That is my Express code (very simple for testing purposes); now using EJS I want to gather this data which I know to render on the page is simply
<%= myVar %>
But I need to be able to gather this data in JavaScript (if possible within a .js file) but for now just to display the variable in an Alert box I have tried
In Jade it is like alert('!{myVar}') or !{JSON.stringify(myVar)}. Can I do something similar in EJS. I don't need any field like <input type=hidden> and taking the value of the field in javascript. If anyone can help be much appreciated

You could use this (client-side):
<script>
var myVar = <%- JSON.stringify(myVar) %>;
</script>
You could also get EJS to render a .js file:
app.get('/test.js', function(req, res) {
res.set('Content-Type', 'application/javascript');
res.render('testPage', { myVar : ... });
});
However, the template file (testPage) would still need to have the .html extension, otherwise EJS won't find it (unless you tell Express otherwise).
As #ksloan points out in the comments: you do have to be careful what myVar contains. If it contains user-generated content, this may leave your site open for script injection attacks.
A possible solution to prevent this from happening:
<script>
function htmlDecode(input){
var e = document.createElement('div');
e.innerHTML = input;
return e.childNodes.length === 0 ? "" : e.childNodes[0].nodeValue;
}
var myVar = JSON.parse(htmlDecode("<%= JSON.stringify(myVar) %>"));
</script>

The main difficulty here is to avoid XSS risks if myVar contains quotes, or </script> for example. To avoid this problem, I propose to use Base64 encoding after JSON.stringify. This would avoid all risks related to quotes or HTML tags since Base64 only contains "safe" characters to put in a quoted string.
The solution I propose:
EJS file:
<script>
var myVar = <%- passValue(myVar) %>
</script>
which will render into something like (for example here myVar = null):
<script>
var myVar = JSON.parse(Base64.decode("bnVsbA=="))
</script>
Server-side NodeJS:
function passValue(value) {
return 'JSON.parse(Base64.decode("' + new Buffer(JSON.stringify(value)).toString('base64') + '"))'
}
Client-side JS (this is an implementation of Base64 decoding that works with Unicode, you can use another if you prefer but be careful if it supports Unicode):
var Base64={_keyStr:"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",encode:function(e){var t="";var n,r,i,s,o,u,a;var f=0;e=Base64._utf8_encode(e);while(f<e.length){n=e.charCodeAt(f++);r=e.charCodeAt(f++);i=e.charCodeAt(f++);s=n>>2;o=(n&3)<<4|r>>4;u=(r&15)<<2|i>>6;a=i&63;if(isNaN(r)){u=a=64}else if(isNaN(i)){a=64}t=t+this._keyStr.charAt(s)+this._keyStr.charAt(o)+this._keyStr.charAt(u)+this._keyStr.charAt(a)}return t},decode:function(e){var t="";var n,r,i;var s,o,u,a;var f=0;e=e.replace(/[^A-Za-z0-9\+\/\=]/g,"");while(f<e.length){s=this._keyStr.indexOf(e.charAt(f++));o=this._keyStr.indexOf(e.charAt(f++));u=this._keyStr.indexOf(e.charAt(f++));a=this._keyStr.indexOf(e.charAt(f++));n=s<<2|o>>4;r=(o&15)<<4|u>>2;i=(u&3)<<6|a;t=t+String.fromCharCode(n);if(u!=64){t=t+String.fromCharCode(r)}if(a!=64){t=t+String.fromCharCode(i)}}t=Base64._utf8_decode(t);return t},_utf8_encode:function(e){e=e.replace(/\r\n/g,"\n");var t="";for(var n=0;n<e.length;n++){var r=e.charCodeAt(n);if(r<128){t+=String.fromCharCode(r)}else if(r>127&&r<2048){t+=String.fromCharCode(r>>6|192);t+=String.fromCharCode(r&63|128)}else{t+=String.fromCharCode(r>>12|224);t+=String.fromCharCode(r>>6&63|128);t+=String.fromCharCode(r&63|128)}}return t},_utf8_decode:function(e){var t="";var n=0;var r=c1=c2=0;while(n<e.length){r=e.charCodeAt(n);if(r<128){t+=String.fromCharCode(r);n++}else if(r>191&&r<224){c2=e.charCodeAt(n+1);t+=String.fromCharCode((r&31)<<6|c2&63);n+=2}else{c2=e.charCodeAt(n+1);c3=e.charCodeAt(n+2);t+=String.fromCharCode((r&15)<<12|(c2&63)<<6|c3&63);n+=3}}return t}}

if you have more complex objects like an array, you can do this :
<% if (myVar) { %>
<script>
myVar = JSON.parse('<%- JSON.stringify(myVar) %>');
</script>
<% } %>
otherwise, previous solutions you have seen will not work

Try this:
<script type="text/javascript">
window.addEventListener('load', function(){
alert('<%= myVar %>');
});
</script>

Heres how i made it work,
in node js pass the json like this
let j =[];
//sample json
j.push({data:"hi});
res.render('index',{json:j});
now in js function
var json = JSON.parse('<%- JSON.stringify(json) %>');
This worked well for me

Per the documentation here:
Go to the Latest Release, download ./ejs.js or ./ejs.min.js.
Include one of these on your page, and ejs.render(str).

In the accepted solution JSON.parse will fail if myVar has a property with value with unescaped double quote. So better traverseObj and escape each string property.
Here is a function that covers my case:
function traverseObj (obj, callback)
{
var result = {};
if ( !isArray(obj) && !isObject(obj) ) {
return callback(obj);
}
for ( var key in obj ) {
if ( obj.hasOwnProperty(key) ) {
var value = obj[key];
if (isMongoId(value)){
var newValue = callback(value.toString());
result[key] = newValue;
}
else if (isArray ( value) ) {
var newArr = [];
for ( var i=0; i < value.length; i++ ) {
var arrVal = traverseObj(value[i], callback);
newArr.push(arrVal);
}
result[key] = newArr;
}
else if ( isObject(value) ) {
result[key] = traverseObj(value, callback);
}
else {
var newValue = callback(value);
result[key] = newValue;
}
}
}
return result;
};
Than in ejs you simply has to:
<%
var encodeValue = function(val) {
if ( typeof val === 'string' ) {
return sanitizeXSS(val); //use some library (example npm install xss)
}
return val;
}
var encodedProduct = ejs_utils.traverseObj(product, encodeValue);
%>
and now you can transport is safely with unescaped syntax
window.product = <%-JSON.stringify(encodedProduct)%>;

I had the similar problem. i got the value
var inJavascript = JSON.parse("<%= myVar %>");

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));

is there way to lint a specific variable name with eslint

For example, I want to eliminate a specific variable name like $abc or '$abc', if it exist anywhere, we will throw a linting error. Its specifically for es6 code or just javascript code.
How can I do that in eslint? is it possble?
If its not what is the alternative I can do to check that without pollute my code base?
You can create your own eslint rule as mentioned in the comments. Here is a small example that reports all identifiers (excluding property names) with name foo:
export default function(context) {
return {
Identifier(node) {
if (
node.name === 'foo' &&
(
node.parent.type !== 'MemberExpression' ||
node.parent.computed ||
node.parent.object === node
)
) {
context.report(node, 'Do not use the variable name "foo"');
}
}
};
};
Live example: http://astexplorer.net/#/Lmzgbm2iRq
You could traverse the codebase and check all the files for the presence of the variable you wish to eliminate. It's perhaps a bit heavyweight for what you need but it might be an option.
Something like this should do the trick. You will have to replace $bad_variable_name with whatever your actual
variable is. You will also have to do something to make your build fail (if desired)
var fs = require('fs');
var checkDir = (dir) => {
var files = fs.readdirSync(dir);
files.forEach((file) => {
var path = dir + '/' + file;
var stat = fs.statSync(path);
if (stat && stat.isDirectory()) {
checkDir(path);
} else {
if(path.endsWith('this-file.js')){ //the file where this code is
return;
}
var fileContents = fs.readFileSync(path);
if(fileContents.indexOf('$bad_variable_name') > -1){
console.log('$bad_variable_name found in ' + path);
//do something here to fail your build
}
}
});
};

Javascript Rewrite Config File

I have a config.js file which I believe is JSON which is called when the application first starts:
var config={};
config.user = [
{id:'JSMITH', priceModify:'true'},
{id:'JBLOGGS', priceModify:'false'},
]
config.price = [
{id:"price01", name:"priceName01", primary:"57.25", secondary:"34.54"},
{id:"price02", name:"priceName02", primary:"98.26", secondary:"139.45"},
{id:"price03", name:"priceName03", primary:"13.87", secondary:"29.13"}
]
To pull / push data I just use the following:
// Read
var curPrice = config.price[0].primary;
// Write
config.price[0].primary = "98.24";
How do I go about exporting the config file with the new value so that it will load next time the application is opened? I can use the file system object to write the file, I just don't understand how I would export everything (and preferably keep the same format).
I originally thought about reading the whole config file into a variable, cycling through to find the required block, id, and key and replacing the value, then writing the whole thing back, but I can't seem to figure out how to replace that specific value only.
Any help would be greatly appreciated
Edit Apologies, I forgot to mention that this application is completely offline and uses local directories
Solution
I stumbled across a few solutions to different issues which, when combined, gave me the perfect solution. First we cycle the Javascript object, building an array of the detail and then converting the array to a string:
vMethod.convertToText = function(obj) {
var string = [];
var output = '';
var count= 0;
var countTotal = 0;
if (typeof(obj) == "object" && (obj.join == undefined)) {
count= 0;
countTotal = 0;
string.push("{");
for (prop in obj) {
countTotal++;
}
for (prop in obj) {
if(count==countTotal - 1) {
string.push(prop, ": ", vMethod.convertToText(obj[prop]),'}\r\n');
} else {
string.push(prop, ": ", vMethod.convertToText(obj[prop]), ",");
}
count++;
};
} else if (typeof(obj) == "object" && !(obj.join == undefined)) {
count= 0;
countTotal = 0;
string.push("[\r\n")
for (prop in obj) {
countTotal++;
}
for(prop in obj) {
if(count==countTotal - 1) {
string.push(vMethod.convertToText(obj[prop]),'];\r\n');
} else {
string.push(vMethod.convertToText(obj[prop]), ",");
}
count++;
}
} else if (typeof(obj) == "function") {
string.push(obj.toString())
} else {
string.push(JSON.stringify(obj))
}
output = string.join("").toString();
//output = output.slice(1, -1);
return output;
}
Then we clean the array (neccessary for me to remove excess characters)
vMethod.cleanConfigText = function() {
var outputText = vMethod.convertToText(config);
outputText = outputText.slice(1, -1);
outputText = 'var config = {};\r\n'+outputText;
outputText = outputText.replace('user:','config.user =');
outputText = outputText.replace(',price:','config.price =');
outputText = outputText.slice(0, -2);
outputText = outputText.replace(/"/g, "'")
return outputText;
}
Finally a function to export the object into my config.js file:
vMethod.writeToConfig = function() {
vObject.fileSystem = new ActiveXObject('Scripting.FileSystemObject');
vObject.fileSystemFile = vObject.fileSystem.CreateTextFile('source\\js\\config.js',true);
vObject.fileSystemFile.Write(vMethod.cleanConfigText());
vObject.fileSystemFile.Close();
delete vObject.fileSystemFile;
delete vObject.fileSystem;
}
So when I want to export a change in the config, I just call:
vMethod.writeToConfig();
The only difference in the file format is that the commas appear at the start of a trailing line rather than the end of a preceding line but I can live with that!
Edit Turns out I'm anally retentive and the commas were bugging me
Added these to the clean up function and now the config is identical to before but without the indent
outputText = outputText.replace(/[\n\r]/g, '_');
outputText = outputText.replace(/__,/g, ',\r\n');
outputText = outputText.replace(/__/g, '\r\n');
Thank you to those that looked at the question and tried to help, very much appreciated.
Edit
DO NOT READ THE SOLUTION ABOVE, IT IS IN THE WRONG PLACE AND THERFORE IS NOT A VALID ANSWER. YOU'VE BEEN WARNED.
You can use a very popular npm package: https://www.npmjs.com/package/jsonfile . There are many but I've choosen this one.
Usually config stuff should be in json or .env files.
Now, all you have to do is use jsonfile's API to read/write JSON and parse (the package does the serialization/deserialization) it at the beginning when the application starts.
Example:
var jsonfile = require('jsonfile');
var util = require('util');
var config = null;
var file = './config.json';
// Reading
jsonfile.readFile(file, function(err, obj) {
config = obj;
});
// Writing
// Edit your config blah blah
config.user = [
{id:'JSMITH', priceModify:'true'},
{id:'JBLOGGS', priceModify:'false'},
];
config.price = [
{id:"price01", name:"priceName01", primary:"57.25", secondary:"34.54"},
{id:"price02", name:"priceName02", primary:"98.26", secondary:"139.45"},
{id:"price03", name:"priceName03", primary:"13.87", secondary:"29.13"}
];
jsonfile.writeFile(file, config, function (err) {
if(err) return err;
console.log('Config saved to file!');
});

Knockout to keep XML node capitalization

I'm currently using Knockout to create some XML that's consumed by a third-party tool on the go.
Rather straight forward,
var queryString = "";
var query = [
'<Values data-bind="foreach: items, attr: {\'data-bind\': false}">',
'<Value data-bind="text: $data, attr: {\'data-bind\': false}"></Value>',
'</Values>'
];
var queryTemplate = query.join("");
var tmpDiv = document.createElement("div");
tmpDiv.innerHTML = queryTemplate;
ko.applyBindings({
field: field,
items: items
}, tmpDiv);
queryString = tmpDiv.innerHTML;
However, to my great dismay, the output nodes are all lowercase:
<values>
<value>1778</value>
</values>
In general web work the above isn't an issue, however the third-party tool is capitalization sensitive, so it's crucial for the nodes to be formatted as initially specified:
<Values>
<Value>1778</Value>
</Values>
Is there something in Knockout's manual that I missed? Is there an easy workaround?
As helpfully pointed out in the question comments by dperry, this is indeed an HTML vs XML issue. Using jQuery's parseXML() and binding to the
resulting elements helps solve the issue easily:
var tmpDiv = $.parseXML(queryTemplate);
And then later simply bind to tmpDiv.documentElement and use its innerHTML instead.
If you're not using jQuery, you can resolve to simply using their implementation of the above function, might be outdated, original licensing applies:
// Cross-browser xml parsing
parseXML: function( data ) {
var xml, tmp;
if ( !data || typeof data !== "string" ) {
return null;
}
try {
if ( window.DOMParser ) { // Standard
tmp = new DOMParser();
xml = tmp.parseFromString( data , "text/xml" );
} else { // IE
xml = new ActiveXObject( "Microsoft.XMLDOM" );
xml.async = "false";
xml.loadXML( data );
}
} catch( e ) {
xml = undefined;
}
if ( !xml || !xml.documentElement || xml.getElementsByTagName( "parsererror" ).length ) {
jQuery.error( "Invalid XML: " + data );
}
return xml;
}

How to parse a text like XML to a javascript object

I created a function to do this.
var text="adsf [name]Victor[/name] dummytext [name]Elliot[/name] asdf [name]Jake[/name] asdf [foo]bar[/foo]";
alert( readTags(text,'name') ); //Victor,Elliot,Jake
alert( readTags(text,'foo') ); //bar
but now I like to implement a function that receive a string like this
[person]
[name]jake[/name]
[age]12[/age]
[/person]
and return a object like this
var object={};
object['person']={};
object['name']='jake';
object['age']='12';
return(object);
but I don't know how to loop through the text. How to deal with starting and ending tags?
like
[tag] [tag]value[/tag] [/tag]
I thought to find starting tag from left and ending tag from the right using indexOf('[tag]') and lastindexOf('[/tag]')
but doesn't work in this situation
[tag]value[/tag] [tag]value[/tag]
this is the previous function
function readTags(str,property){
var beginTag='['+property+']';
var endTag='[/'+property+']';
var values=new Array(0);
while(str.indexOf(beginTag)!=-1){
values[values.length]=strBetween(str,beginTag,endTag);
str=str.substring(str.indexOf(endTag)+endTag.length);
}
return(values);
}
function strBetween(string,strBegin,strEnd){ //StrBetween("abcdef","b","e") //return "cd"
var posBegin, posEnd;
posBegin=string.indexOf(strBegin);
string=string.substring(posBegin + strBegin.length);
posEnd=string.indexOf(strEnd);
string=string.substring(0,posEnd);
if ((posBegin==-1)||(posEnd==-1)){
return(null);
}else{
return(string);
}
}
Unless you have a good reason not to use JSON, don't do this. JSON handles all of those problems very well and can be floated around from server to client and vice versa quite easily.
But since this seems fun, I'll try and see if I can whip up an answer.
Since your structure resembles XML, just replace the brackets with < and > and parse it like XML:
text = text.replace('[', '<').replace(']', '>');
if (typeof DOMParser != "undefined") {
var parser = new DOMParser();
var xml = parser.parseFromString(text, 'text/xml');
} else {
var xml = new ActiveXObject('Microsoft.XMLDOM');
xml.async = 'false';
xml.loadXML(text);
}
Now xml holds a DOMDocument that you can parse:
xml.getElementsByTagName('person').childnodes;
Try this possibly-working code (didn't test):
function createObject(element) {
var object = {};
if (element.childNodes.length > 0) {
for (child in element.childnodes) {
object[element.tagName] = createObject(child);
}
return object;
} else {
return element.nodeValue;
}
}
I thought this would be interesting to do without a third-party parser, so I built me a simple one:
function parse(code)
{
var obj = {},
cur = obj,
stack = [];
code.replace(/\[([^\]]+)\]|([^\[]*)/g, function (match, tagName, text) {
if (tagName)
{
if (tagName.charAt(0) == "/")
{
/* end tag */
cur = stack.pop();
}
else
{
/* start tag */
stack.push(cur);
cur = cur[tagName] = {};
}
}
else
{
cur["#text"] = text;
}
});
return obj;
}
var obj = parse(text);
JSON <=> XML http://code.google.com/p/x2js/

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