Develop Reference

How can I convert the string value of a jQuery object into an actual jQuery object?

I have this string in my JS code right now:
newWords = '$(p span.word[style="--' + paraIndex + 'word-index:undefined"], p span.whitespace[style="--' + paraIndex + 'word-index:undefined"])';
I want to convert this string into a jQuery object that I can use do identify those specific elements.
I also saw the eval() function. That looks like it does what I want it to, but is super unsafe/unsecure.
Does anyone know a safe way to do this?

The simplest solution is to remove $( and ) and pass the remaining string as an argument to $():
var paraIndex = 0;
var newWords = '$(p span.word[style="--' + paraIndex
+ 'word-index:undefined"], p span.whitespace[style="--'
+ paraIndex + 'word-index:undefined"])';
var jQ = $(newWords.slice(2, -1));
console.log(jQ);
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

Problems in Subscription of global event in JavaScript

I have the following JavaScript Code, I have some queries on these lines,
what does this lines .events.slice (-1)[0][0] means?
and nodes_params += "&ns=" + GLOBAL_EVENT + "," + start_from + ",-,-"; this lines as well?
What does the Subscription of the global events means?
The whole code is too big, but I can post some of the parts of the code, in case it is not understable.
// Subscribe to the global events
var start_from = "0";
if (nodes[GLOBAL_EVENT].events && nodes[GLOBAL_EVENT].events.length > 0) {
start_from = nodes[GLOBAL_EVENT].events.slice(-1)[0][0];
}
nodes_params += "&ns=" + GLOBAL_EVENT + "," + start_from + ",-,-";

1 - events is on array and events.slice(-1) returns the last element in this array, witch seems to be an multidimensional array itself ,and [0][0] returns the first element in the first array.
2 - its a simple string concatenation, += mean appending to the existing variable instead of replacing it
3 - can't say for sure, it depends on what the other codes are

Getting NaN Error and undefined Error

I have a Problem with my push function in JavaScript.
<script type="text/javascript">
var myArr = []
var len = myArr.length
$.getJSON('daten.json', function(data) {
$.each(data,function(key,value) {
for(var i = 0; i <= len; i++){
myArr.push("<p>" + value.Name+i ," ", value.Nachname+i + "</p>")
}
})
$('.content').html(myArr.join(''))
})
</script>
I need to convert value.Name+i like this = value.Name0, value.Name1 and so on. I got a JSON File and the Keys are Dynamic, so the first entry got Name0 the second Name1 and so on. Now I must print the JSON file on my html page, but how I can write this line:
myArr.push("<p>" + value.Name+i ," ", value.Nachname+i + "</p>")
with my var i which increment in the loop, to call the Keys in my JSON file?
Like value.Name0. Doing value.Name+i and value.Name.i does not work.

It seems to me what you're looking for is something like this:
myArr.push("<p>" + value['Name'+i] ," ", value['Nachname'+i] + "</p>")
This portion of javascript is covered pretty nicely here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_Objects

Take the object property in a variable, use condition to check if it has value or not then concat it
var nameval = value.name;
then use in your javascript variable
nameval+i

You need to convert your i (integer value) to string prior to adding it.
use:
value.Name + i.toString()
here's the jfiddle link: http://jsfiddle.net/kpqmp49o/

Removing quotes from a string / an alternative to string

I have dropDown element which takes the options in the format
ctrlOptions:{0:'String',1:'int'}
in addition to simple data types i have user defined data types hence i want to populate this dynamicaly . so i used a loop and concatenation
var dropDown = "{"
for(var i=0;i<dataTypesList.length;i++){
if(i == dataTypesList.length-1){
dropDown = dropDown + i + ":" + "'" + dataTypesList[i].Name + "'}";
}else{
dropDown = dropDown + i + ":" + "'" + dataTypesList[i].Name+ "'" + ",";
}}
This yields be the options in required format but along with quotes around it like
ctrlOptions:"{0:'String',1:'int'}"
i want to remove the double quotes i tried with replace it diesnt seem to help. how can i achieve this can i use any other way.

What you want to create is an object & not a string.
So wildly guessing from your code, that the input dataTypesList looks something like this:
dataTypesList = [{Name:'String'}, {Name:'int'}]
You should use :
var dropDown = {};
for(var i=0;i<dataTypesList.length;i++)
dropDown[i] = dataTypesList[i].Name;
And then Output is an object :
{0: "String", 1: "int"}

you can use JSON.parse to convert the options string from string json to object json:
Using your code (slightly modified):
var dropDown = "{"
for(var i = 0; i < dataTypesList.length; i++)
{
if(i === dataTypesList.length - 1)
{
dropDown += i + ":'" + dataTypesList[i].Name + "'}";
}
else
{
dropDown += i + ":'" + dataTypesList[i].Name + "',";
}
}
// later...
ctrlOptions: JSON.parse(dropDown);
Verify your target browsers are compatible: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse
If not, there are some libraries compatible with older browsers that do the same thing. JSON2 is recommended by the author for out-of-date browsers: https://github.com/douglascrockford/JSON-js

jQuery - parsing JSON data - Having trouble with variable name

My first delve into working with JSON data. I have a bit of experience using jQuery though.
I'm posting to this URL (tumblr api): jyoseph.com/api/read/json
What I'm trying to do is output the json that gets returned. What I have so far:
$(document).ready(function(){
$.getJSON("http://jyoseph.com/api/read/json?callback=?",
function(data) {
//console.log(data);
console.log(data.posts);
$.each(data.posts, function(i,posts){
var id = this.id;
var type = this.type;
var date = this.date;
var url = this.url;
var photo500 = this.photo-url-500;
$('ul').append('<li> ' +id+ ' - ' +type+ ' - ' +date+ ' - ' +url+ ' - ' +photo500+ ' - ' + ' </li>');
});
});
});
See my jsbin post for the entire script: http://jsbin.com/utaju/edit
Some of the keys from tumblr have "-" hyphens in them, and that seem to be causing a problem. As you can see "photo-url-500" or another "photo-caption" is causing the script to break, it's outputting NaN.
Is there a problem with having hyphens in the key names? Or am I going about this all wrong?

If there are dashes in the names you'll need to access them differently. Change var photo500 = this.photo-url-500; to read var photo500 = this["photo-url-500"];.

Please note it is best not to append inside each iteration. Better to append to a string or push to an array then append once after the iterator has finished. Appending to the dom is expensive.

Use the bracket notation to access the members:
var photo500 = this['photo-url-500'];