Develop Reference

How to replace 'special' characters in a string of code with an expanded piece of that same code?

I'm creating a chrome extension that basically finds a string of text such as this (note the different numbers):
id%22%3A99986%2C%22name%22%3A%22null%22%7D%2C%7B%22id%22%3A1002938%2C%22name%22%3A%22null%22%7D%2C%7B%22
and then usese javascript to swap that text above with this:
id%22%3A77764%2C%22name%22%3A%22null%22%7D%2C%7B%22id%22%3A77984%2C%22name%22%3A%22null%22%7D%2C%7B%22id%22%3A87746%2C%22name%22%3A%22null%22%7D%2C%7B%22
I can't manage to make this work whatsoever. All I'm able to do is swap out the ID numbers and replace individual parts of the code whereas I want to improve it by replacing with larger pieces of code. Can someone help me get past this because I'm confused.
Here is the code that works for me:
document.body.innerHTML = document.body.innerHTML.replace(/99986/g, '77764');
What I'm trying to do is to replace one piece of code with two pieces of code (obviously wrong but it's clear what I'm trying to do):
document.body.innerHTML = document.body.innerHTML.replace(/id%22%3A99986%2C%22name%22%3A%22null%22%7D%2C%7B%22/g, 'id%22%3A77764%2C%22name%22%3A%22null%22%7D%2C%7B%22id%22%3A77984%2C%22name%22%3A%22null%22%7D%2C%7B%22');
Update 1:
Thank you Emeeus, your code worked great! Unfortunately I made an error in my example so I had to fix it up a bit from my end. This is the new code using your layout:
var strA =
"%7Bid%22%3A1001%2C%22name%22%3A%22The+Antique+Store%22%7D%2C%7B%22id%22%3A1010%2C%22name%22%3A%22Clothes%22%7D%2C%7B%22id%22%3A1349%2C%22name%22%3A%22Old+Store%22%7D";
var strB = "%7Bid%22%3A1001%2C%22name%22%3A%22The+Modern+Store%22%7D%2C%7B%22id%22%3A1010%2C%22name%22%3A%22Clothes%22%7D%2C%7B%22id%22%3A1349%2C%22name%22%3A%22New+Store%22%7D";
var arrA = JSON.parse(decodeURIComponent(',{""' + strA + '",:""}'));
var arrB = JSON.parse(decodeURIComponent(',{""' + strB + '",:""}'));
console.log(arrA)
console.log(arrB)
var res = Object.assign(arrA, arrB);
console.log(encodeURIComponent(JSON.stringify(res)))
But I'm met with this error "Error: Unexpected token , in JSON at position 0". Any ideas?

I think you should check if the typeof string you are trying to replace is string. I tested, check if that solves your problem.
See screenshot:

Your strings are parts of a JSON URI-encoded, so I suggest first to decode the strings an then parse them using JSON.parse, then you could work with objects literals, which is easier most of times, here an example:
var strA = "id%22%3A99986%2C%22name%22%3A%22null%22%7D%2C%7B%22id%22%3A1002938%2C%22name%22%3A%22null%22%7D%2C%7B%22";
var strB = "id%22%3A77764%2C%22name%22%3A%22null%22%7D%2C%7B%22id%22%3A77984%2C%22name%22%3A%22null%22%7D%2C%7B%22id%22%3A87746%2C%22name%22%3A%22null%22%7D%2C%7B%22";
var arrA = JSON.parse(decodeURIComponent('[{"' + strA + '":""}]'));
var arrB = JSON.parse(decodeURIComponent('[{"' + strB + '":""}]'));
console.log(arrA)
console.log(arrB)
var res = Object.assign(arrA, arrB);//<-- example
console.log(encodeURIComponent(JSON.stringify(res)))//<-- you could encode the result again

Jquery & JSON: Replace section of JSON array

I've been reading a ton on this and can't seem to find a solution that works for me. I am building a drag and drop menu system and saving the structure to the db as JSON.
I have a hidden field as part of a form that submits to the db. This hidden field has the full JSON string in it.
When I update a particular node/menu item, I want to search the value of the hidden text field, find the 'section' of JSON I want to update and replace it with the new values.
What is the best solution for this? grep? replaceWith?
Example before and after JSON
// This is the full json string
[{"title":"Cool link","link":"link","cssclass":"","cssid":"","id":"1399209929525"},{"title":"New link","link":"new-link.html","cssclass":"","cssid":"","id":"1399209790202"},{"title":"Another link","link":"cool","cssclass":"","cssid":"","id":"1399209834496"}]
// This is the updated section
[{"title":"Another link changed","link":"cool","cssclass":"","cssid":"","id":"1399209834496"}]
So I have the updated section with a unique ID to search against.
A simple solution would be something like this, but it doesn't work like that.
var currentsection = /'{"title":"' + edittitle + '","link":"' + editurl + '","cssclass":"' + editcssclass + '","cssid":"' + editcssid + '","id":"' + editid + '"}'/;
var newsection = /'{"title":"' + updatedtitle + '","link":"' + updatedlink + '","cssclass":"' + updatedcssclass + '","cssid":"' + updatedcssid + '","id":"' + updatedid + '"}'/;
$("#menu_items").val().find(currentsection).replaceWith(newsection);
What do you think the best approach is? Many thanks for taking the time out to help. I really appreciate it.

I think you should create your JSON object, and work with it. In this way it would be easy to change values and also save it as you want ;)
For example :
var json = YOUR JSON HERE;
var obj = JSON.parse(json);
// now you can update values as you want
// for example with example title
obj[0].title = "updatetitle";
And then, before sending your JSON, you may want to convert it in plain text
var json = JSON.stringify(obj);

Changing Attributes of json object in Android application (Titanium)

Hi I am developing Android application using Titanium.I want to change value of particular attributes of json object.I tried following code :
var row_jsonfeed = this.responseText;
var jsonfeed = eval('('+row_jsonfeed+')');
my jsonfeed object look like this :
{"feeds":
[
{"username":"abc","user":"abc","feed":{"description":"dss","id":660,"user_id":1}},
{"username":"bcd","user":"bcd","feed":{"description":"dddd","id":659,"user_id":1}}
]
}
I want to change username value so I tried like this:
jsonfeed.feeds[0].username = "xyz";
alert(jsonfeed.feeds[0].username);
But it's not working.It not giving me changed value of username.Any other alternative way to do this. Instead of eval I also tried JSON.parse but that also not working.So i need proper way to do this.Thank you in advance.

I think the problem is with your call to eval. You forgot to concatenate your parens:
eval('(' + row_jsonfeed + ')');

Mixing variables with text in Javascript

Im trying (unsuccessfully) to prepend the following content to a div:
var entry = $('textarea').val();
var formated = '<div class="newsfeed_entry"><p>' . entry . '</p></div>';
$('#entry_container').prepend(formated);
I think the reason it isn't work is related to the way I am mixing variables and text. I looked at the documentation but I can't figure out what the issue is.

Try
var entry = $('textarea').val();
var formated = '<div class="newsfeed_entry"><p>' + entry + '</p></div>';
$('#entry_container').prepend(formated);

. is for object property lookup in JavaScript. You may have been in the PHP world for too long.
You can concatenate strings in JavaScript with the String object's concat() method or with + (it is overloaded to do arithmetic addition and string concatenation).

How to parse JSON that has inner layers using Javascript?

I can eval simple JSON with javascript.
var json = '{"amount":"50","id":"3"}';
var out = eval("{" + json + "}");
Now I am using JPA with REST and JSON-nized query result would include table name which makes
JSON having inner JSON so simple eval wouldn't work.
{"inventory":{"amount":"50","id":"3"}}
I've looked around the web for solution but can't find my case.
Should I just do string manipulation and extract {"amount":"50","id":"3"} part?
Or is there other way?

Yes, there is another (better) way! Use JSON.parse() to parse your JSON and get your object out:
var obj = JSON.parse(jsonString);
//then, for example...
var amount = obj.inventory.amount;
For older browsers (IE <8 for example) without native JSON support, include json2.js so this above still works.

Even this should work:
var json = '{"inventory":{"amount":"50","id":"3"}}';
var out = eval("{" + json + "}");
alert(out.inventory.amount);
But better to use JSON.parse

Aniway, I think that the proper way to perform a simple eval is to have the json string surrounded with parenthesis, not curly brackets...
var out = eval("(" + json + ")");
Cf. https://github.com/douglascrockford/JSON-js/blob/master/json.js :
// In the third stage we use the eval function to compile the text into a
// JavaScript structure. The '{' operator is subject to a syntactic ambiguity
// in JavaScript: it can begin a block or an object literal. We wrap the text
// in parens to eliminate the ambiguity.
j = eval('(' + text + ')');