How to get the Object from a string?
I written a localStorage util, in it there are get and set methods.
in the set method:
function fnGet(name){
var getVal=storage.getItem(name);
if(getVal==null){
return console.log('the localstorage did\'t have'+name);
}
if((getVal.split(':-:')).lenght>1){
return eval('('+getVal.split(':-:')[0]+')');
}
return getVal.split(':-:')[0];
}
You can ignore the :-:, it is the separator of the saved data and timestamp.
there is a problem, if the data is stored a JavaScript Object, such like this:
'{"pk":1,"username":"test01","email":"","first_name":"","last_name":""}:-:1521381469910'
when I use the get method, it will become like this:
'{"pk":1,"username":"test01","email":"","first_name":"","last_name":""}'
How can I get to the JavaScript Object?
How to optimize my get method?
JSON.parse on your response from the store. localStorage stores everything as strings so you would need to stringify the object at first, as Im supposed you do as otherwise you wouldnt have been able to save it to the store.
Then to retrieve it you would need to parse it to get the javascript object again.
Two things:
Use JSON.parse() instead of eval; it's not only safer, but more descriptive as to what your intent is. Note: this requires using JSON.stringify() on the data being saved in localStorage
Correct your spelling errors; you would never get to the eval/parser block because your length was spelled "lenght"
function fnGet(name) {
let getVal = storage.getItem(name)
if (getVal == null) {
return console.log(`the localstorage did't have: ${name}`);
}
let val = getVal.split(':-:'); // for performance cache the split
if (val.length > 1) { // Spelling error: "lenght" -> length
return JSON.parse(val[0]);
}
return val[0];
}
LocalStorage saves the data stringified. So you should use JSON.parse(yourVariable) to get the data back as JSON
function fnGet(name) {
var getVal = storage.getItem(name);
if (getVal == null) {
return console.log('the localstorage did\'t have' + name);
}
if ((getVal.split(':-:')).lenght > 1) {
return eval('(' + JSON.parse(getVal.split(':-:')[0]) + ')');
}
return getVal.split(':-:')[0];
}
all you needed was JSON.parse which takes a string as an argument and if its a valid object string ,returns an object else throws an error
Related
I am reading cookie value for Cookie Consent "CookieScriptConsent" which can store values in different ways such as
{"action":"reject","categories":"[]"}
{"action":"accept","categories":"[]"}
{"action":"accept"}
{"action":"accept","categories":"[\"performance\",\"targeting\",\"functionality\"]","key":"58abddd4-493e-499a-9711-67644adc39af"}
{"action":"accept","categories":"[\"performance\"]","key":"24b56441-d831-4cd1-8e5f-47353257f500"}
I am using a cookie reading plugin which reads cookie value Cookies.get('CookieScriptConsent');
I store this value in variable and now i need to read values if cookie was accepted or rejected.
var string= Cookies.get('CookieScriptConsent');
var res = str.match(/accept/gi)
i am using match function of js to see if i find a match, it will return value or null how can i use this if if statement or what is the best way to achieve this
should i use var n = str.indexOf("accept"); as it will give me numeric value which can easily be used in if statement to check if value is greater than 0
If the data stored in the cookie is a JSON object stringified, you can try to parse it and check if the property matches with the value you are looking for:
function getCookieData() {
var cookie = Cookies.get("CookieScriptConsent");
console.log("Raw data: ", cookie);
if (cookie) {
var scriptConsent = JSON.parse(cookie);
if (scriptConsent.action === "accept") {
console.log("Consented!");
} else {
console.log("Rejected!");
}
} else {
console.log("Cookie do not exists");
}
}
This also allows you to check if this particular property has the value.
Hope it helps!
I have a settings.json file that contains following data (where 123456789 is a distinct user id):
{
"123456789":
{"button_mode":true}
}
So what I need to do is push a similar id: {button_mode: value} object to this JSON file in case there's no entry for current user's id. I tried to use lcSettings.push() but obviously it did not work since I have an object, not an array. When I put square brackets instead of curly ones to make it an array, my code doesn't do anything at all.
Here's a snippet of it (Node.js):
var lcSettings = JSON.parse(fs.readFileSync('./settings.json', 'utf8'));
var currentUser = id;
if (lcSettings.hasOwnProperty(currentUser)) {
// in case settings.json contains current user's id check for button_mode state
if (lcSettings[currentUser].button_mode == true) {
// if button_mode is on
} else
if (lcSettings[currentUser].button_mode == false) {
// if button_mode is off
}
} else {
// in case there's no entry for current user's id
// here's where I need to push the object for new user.
}
fs.writeFileSync('./settings.json', JSON.stringify(lcSettings))
Does anybody have ideas on how it can be implemented? Any help appreciated.
You can use bracket notation to add a dynamic property to an object:
lcSettings[id] = { button_mode: false };
You may also want to verify that settings.json is not empty otherwise the JSON.parse() will fail. In this case, you would want to initialize lcSettings to an empty object (lcSettings = {}) so the above will work.
To 'push' elements to an object you simply define them, as in
object['123456789'] = { button_mode: true };
Background
We have much of our data formatted like
var X = {value:'some val',error:'maybe an error',valid:true}
as a result we find ourselves calling X.value ALL the time.
We don't use the .error or .valid nearly as much, but we do use it.
What I want
To quit calling .value everywhere, but to still have access to meta data on a per data point level.
The Question
Is there one of
A) A way to put meta data on a primitive? attaching .error to an int for example? Is it possible for bools or strings?
B) A way to make a class that can be treated as a primitive, providing a specific data member when I do? IE X.value = 5, X+3 returns 8.
C) A better design for our data? Did we just lay this out wrong somehow?
You can set the method toString() to your object and return value.
var X = {
value: 1,
error:'maybe an error',
valid:true,
toString: function() {
return this.value;
}
}
X.value = 5;
console.log(X+3);
You can represent you data as a function object that also has properties:
var X = () => 1;
X.value = 1;
X.error = 'maybe an error';
X.valid = true,
console.log(X()); // 1
console.log(X.valid); // true
For better design you can encapsulate the creation of the data object in another function.
At the moment I have to check every potentially existing parameter separately.
if (req.query.param1 != undefined ) {
}
if (req.query.param2 != undefined ) {
}
if (req.query.param3 != undefined ) {
}
...
To get all query parameter:
Object.keys(req.query)
To get number of all params:
Object.keys(req.query).length
Then you can iterate through all parameters:
for(p in req.query) {
//... do something
}
UPD:
surround your request with quotes to make right query
curl -X GET "localhost:9090/mypath?param1=123¶m2=321"
without quotes the & in terminal makes the command run in the background.
If you hit /mypath?param1=5¶m2=10, then the request.query will yield {param1: 5, param2:10}.
This means that the request.query is a JavaScript object with the key as the name of the param, and value as the value of the param. Now you can do anything with it as you want: Find the length or iterate over it as follows:
for (var key in request.query) {
if (request.query.hasOwnProperty(key)) {
alert(key + " -> " + request.query[key]);
}
}
Finding only the length might not work for you that well because you may have param1 and param3, with param2 missing. Iterating will be better IMO.
You want the number of non-undefined params right?
It is as simple as this;
var no = 0;
for (var key in req.query) {
if(req.query[key]) no++;
}
In a JQuery getJSON call, how can I tell the length of the JSON that's returned?
function refreshRoomList() {
$.getJSON('API/list_rooms',
function (rooms) {
if (rooms.length > 0) {
$("#existing-room-list").empty();
$("#join-existing-room").text("Join existing room:"); // this shouldn't be here
$.each(rooms, function (index, roomName) {
var newChild = sprintf('<li>%s</li>', index, roomName);
$("#existing-room-list").append(newChild);
});
}
else {
$("#join-existing-room").text("No rooms found.");
}
});
}
For some reason this doesn't work, but if I replace rooms.length > 0 with true, the full list of rooms is printed out.
If rooms is empty, it is returned as {}.
If rooms is empty, it is returned as {}.
Thus, it's not an array, but an object. Objects doesn't have a length. There's only one of it. If you want to denote nothing, then rather use null instead of {}. This way you can use if (rooms) instead.
To learn more about JSON, you may find this article useful.
Try this approach instead, in your situation it should be null when empty:
if (rooms) {