I am reading some values from an xml file using JavaScript. Since it is a string, i need to convert it to integer and perform some calculations.
For reading the data from XML file I use this code:
var pop = JSON.stringify(feature.attributes.Total_Pop.value);
which works fine. later I use the following code to convert it to integer:
var popint = parseInt(pop);
This also works fine. But later when I use it to do some math, it returns NAN.
the code I use for Math operation is:
var pop6 = Math.ceil(popint / 30);
What am I doing wrong? any suggestions?
Don't stringify -- just use var pop = feature.attributes.Total_Pop.value;. Calling JSON.stringify wraps the string in extra quotation marks.
var pop = "123"; // "123"
var popint = parseInt(pop); // 123
Vs:
var pop = JSON.stringify("123"); // ""123""
var popint = parseInt(pop); // NaN
Related
Even when I save an integer to embedded data earlier in the survey flow (in previous blocks on different screens), I am not able in Javascript to get the embedded data value, ensure it is parsed as a number/integer, then use it in a loop. Is this something about TypeScript? I didn't see anything about parseInt or ParseInt in the TypeScript documentation.
For example, suppose I do the following:
// Draw a random number
var x = Math.floor(Math.random() * 5);
// Save it in embedded data
Qualtrics.SurveyEngine.setEmbeddedData("foo", x);
// In a later block on a different screen, get the embedded data as an integer
var x_new = "${e://Field/foo}"; // not an int
var x_new = parseInt("${e://Field/foo}"); // doesn't work
var x_new = ParseInt("${e://Field/foo}"); // doesn't work
// Loop using x_new:
for(i = 0; i < x_new; i++) {
console.log(i)
}
Any idea why this isn't working? Perhaps I just don't know how to parseint().
In "normal" JS runtime system, we have parseInt function, the function gets a string (like number string) as a parameter. In this env, we don't support your syntax - "${e://Field/foo}", because it is not a "number string".
In Qualtrics system environment they have parseInt too, but they support their custom syntax "${e://Field/foo}" to get EmbeddedData.
Make sure that your code is running on Qualtrics system environment.
ParseInt is just turning your string into an integer.
Look at the demo below.
let myVar = "${e://Field/foo}"; // This is a string
console.log(myVar); // This prints a string
console.log(parseInt(myVar)); // This prints "NaN", i.e. Not a Number, because the string isn't a representation of a number.
Building a calculator.
var process = "6÷6"; // need to replace division sign with one that javascript can evaluate with
process = encodeURI(process);
process.replace(/%C3%B7/gi,'/'); // replacement step that doesn't work - %C3%B7 is what shows up as the hex divison sign in chrome debugger, not sure why
process = decodeURI(process);
result = eval(process);
You can create an object with properties set to arithmetic operators. Note, .replace() may not be necessary
var map = {"÷":"/"};
var operatorType = "÷";
var process = "6" + map[operatorType] + "6"; // need to replace division sign with one that javascript can evaluate with
process = encodeURI(process);
process.replace(/%C3%B7/gi,'/'); // replacement step that doesn't work - %C3%B7 is what shows up as the hex divison sign in chrome debugger, not sure why
process = decodeURI(process);
result = eval(process);
document.body.innerHTML = result;
The third line of your code is wrong. You have to assign the return value of the replace function to a variable. The easiest way is to assign it to itself:
process = process.replace(/%C3%B7/gi,'/');
So the whole script code would look like this:
var process = "6÷6"; // need to replace division sign with one that javascript can evaluate with
process = encodeURI(process);
process = process.replace(/%C3%B7/gi,'/'); // replacement step now works
process = decodeURI(process);
result = eval(process);
I have this code:
var string = '{"items":[{"Desc":"Item1"},{"Desc":"Item2"}]}';
localStorage.setItem('added-items', JSON.stringify(string));
This code will use localStorage.
Here is now the code to get the stored data:
var retrievedObject = localStorage.getItem('added-items');
My problem now is, how can i get the size of the data items? answer must be 2.
How can i get the "Item1" and "Item2"?
I tried retrievedObject[0][0] but it is not working.
And how to add data on it?
so it will be
{"items":[{"Desc":"Item1"},{"Desc":"Item2"},{"Desc":"Item3"}]}
Can I use JSON.stringify?
var string = '{"items":[{"Desc":"Item1"},{"Desc":"Item2"}]}';
localStorage.setItem('added-items', JSON.stringify(string));
stringify means, take an object and return its presentation as a string.
What you have, is already a string and not a JSON object.
The opposite is JSON.parse which takes a string and turns it into an object.
Neither of them have anything to do with getting the size of an array. When properly coding JavaScript you almost never use JSON.parse or JSON.stringify. Only if serialization is explicitly wanted.
Use length for the size of the array:
var obj = {"items":[{"Desc":"Item1"},{"Desc":"Item2"},{"Desc":"Item3"}]}
console.debug(obj.items.length);
// THIS IS ALREADY STRINGIFIED
var string = '{"items":[{"Desc":"Item1"},{"Desc":"Item2"}]}';
// DO NOT STRINGIFY AGAIN WHEN WRITING TO LOCAL STORAGE
localStorage.setItem('added-items', string);
// READ STRING FROM LOCAL STORAGE
var retrievedObject = localStorage.getItem('added-items');
// CONVERT STRING TO REGULAR JS OBJECT
var parsedObject = JSON.parse(retrievedObject);
// ACCESS DATA
console.log(parsedObject.items[0].Desc);
To bring clarity to future people that may stumble across this question and found the accepted answer to not be everything you hoped and dreamed for:
I've extended the question so that the user may either want to input a string or JSON into localStorage.
Included are two functions, AddToLocalStorage(data) and GetFromLocalStorage(key).
With AddToLocalStorage(data), if your input is not a string (such as JSON), then it will be converted into one.
GetFromLocalStorage(key) retrieves the data from localStorage of said key
The end of the script shows an example of how to examine and alter the data within JSON. Because it is a combination of objects and array, one must use a combination of . and [] where they are applicable.
var string = '{"items":[{"Desc":"Item1"},{"Desc":"Item2"}]}';
var json = {"items":[{"Desc":"Item1"},{"Desc":"Item2"},{"firstName":"John"},{"lastName":"Smith"}]};
localStorage.setItem('added-items', AddToLocalStorage(string));
localStorage.setItem('added-items', AddToLocalStorage(json));
// this function converts JSON into string to be entered into localStorage
function AddToLocalStorage(data) {
if (typeof data != "string") {data = JSON.stringify(data);}
return data;
}
// this function gets string from localStorage and converts it into JSON
function GetFromLocalStorage(key) {
return JSON.parse(localStorage.getItem(key));
}
var myData = GetFromLocalStorage("added-items");
console.log(myData.items[2].firstName) // "John"
myData.items[2].firstName = ["John","Elizabeth"];
myData.items[2].lastName = ["Smith","Howard"];
console.log(myData.items[2]) // {"firstName":["John","Elizabeth"],"lastName":["Smith","Howard"]}
console.log(myData.items.length) // 4
JSON.parse is definitely the best way to create an object but I just want to add if that doesn't work (because of lack of support), obj = eval('(' + str + ')'); should work. I've had a problem with a HTML to PDF converter in the past that didn't include JSON.parse and eval did the trick. Try JSON.parse first.
Access your object: obj.items[0].Desc;
var object = Json.parse(retrievedObject);
Now you can access it just like an array
https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse
If you need more help i have some previous code where i am reading Json from local storage and making a form from that json. This code will help in understanding how to traverse that array
Json stored in localstorage
{"form":[{"element":"input", "type":"text","name":"name","value":"value","min":"2","max":"10"}]}
JavaScript to read that json
function readJson(){
if(!form_created){
add_form();
}
var fetched_json = localStorage.getItem("json");
var obj=JSON.parse(fetched_json);
for(var i=0; i<obj.form.length;i++){
var input = document.createElement(obj.form[i].element);
input.name = obj.form[i].name;
input.value = obj.form[i].value;
input.type = obj.form[i].type;
input.dataset.min = obj.form[i].min;
input.dataset.max = obj.form[i].max;
input.dataset.optional = obj.form[i].optional;
form.insertBefore (input,form.lastChild);
}
alert(obj.form[0].name);
}
i have a json string returned to a hidden value and i want to assign it to a javascript array and print each element of the array.
Json string returned by hdn_client_windows - ["5703","5704"]
Javascript array assignment is as below.
var times = $('#hdn_client_windows').val();
alert(times[0]); // this printed only--> [
alert(times[1]); // this printed only--> "
what am i doing wrong ?
You need to parse the JSON into an array with JSON.parse first:
var times = JSON.parse($('#hdn_client_windows').val());
Since you are already using jQuery, it might be a good idea to defer to $.parseJSON instead just to be on the safe side (full compatibility with old browsers):
var times = $.parseJSON($('#hdn_client_windows').val());
Use $.parseJSON().
var str = '["5703","5704"]';
var times = $.parseJSON( str );
You have to parse the string first using JSON.parse (older browsers might require you to load this in):
var times = JSON.parse($('#hdn_client_windows').val());
alert(times[0]); // Will display first item
alert(times[1]); // Will display second item
You could use jquery's parseJSON() function.
var str = '["5703","5704"]';
var parsed = $.parseJSON( str );
The parsed object now contains the array: ["5703","5704"]
Reference - jQuery.parseJSON( json )
"Takes a well-formed JSON string and returns the resulting JavaScript object."
In JScript, why do I get the error "Object doesn't support this property or method" when I try to convert request.querystring to a string using toString()?
var params = Request.QueryString;
var params = params.toString();
Background info:
I'm trying to convert the querystring to a string so that I can perform a regex replace and remove certain items when they appear in the url.
var param = param.replace(/([?&])(allow)=[\w-]+/g, "");
I recently discovered the solution to this problem.
var params = Request.QueryString;
should be:
var params = Request.QueryString.Item;
There is no need to convert params to a string after that to manipulate the query string. Further you have access to everything in the query string by calling Request.QueryString("param").Item.
Example:
http://www.mysite.com?q=query&name=george
var name = Request.QueryString("name").Item;
I don't know -- weird Microsoft JScript implementation.
I had the same problem.
var strParams = new String(params);
seems to work though.