Develop Reference

Convert array string to array for mapping data

Here is my problem
const data = "[\"https://i.imgur.com/PAYXC2n.jpg\",\"https://i.imgur.com/bEfjjxA.jpg\"]";
I want to convert this string to array,
expected result will be :
res =["https://i.imgur.com/PAYXC2n.jpg","https://i.imgur.com/bEfjjxA.jpg"]
I use it for mapping data in React JS project, so i need to convert this string to array.

Just parse it from JSON:
const
data = "[\"https://i.imgur.com/PAYXC2n.jpg\",\"https://i.imgur.com/bEfjjxA.jpg\"]",
parsed = JSON.parse(data);
console.log(parsed);

Do it:
const dataArr = JSON.parse(data);. This will parse as to object, which is your array (With out "")

Converting json from json_ecode() to a javascript array

I am using the json_encode() in php to return a json object. How can i convert it to a javascript array?
input:
[{"message":"1"},{"message":"2"}]
output
["1", "2"]

this way
const data = '[{"message":"1"},{"message":"2"}]'
const result = JSON.parse(data).map(o=>o.message)
console.log( result )

Parsing data with unknown JSON nodes

I am trying to convert some JSON into a javascript arrays, however, the date is used a key as well as an attribute in the node. I wanted to use a map function to extract the dates, however, I have the extra date key which I don't know ahead of time. Do I have to loop through the keys and parse out the data or is there a clever way I can use javascript functions like map to do it?
var label_Dates = data.map(({date}) => date);
var label_Data = data.map(({totalAssets}) => totalAssets);
JSON data:
2020-03-31: {...}
date: "2020-03-31"
totalAssets: "300280000000.00"
2019-12-31: {...}
date: "2019-12-31"
totalAssets: "306928000000.00"
2019-09-30: {...}
2019-06-30: {...}
2019-03-31: {...}
2018-12-31: {...}
2018-09-30: {...}
2018-06-30: {...}
2018-03-31: {...}

This example shows you have to put all of the values of a JSON object into an array:
var json = {"date1":"aa","date2":"cc"};
const arr = Object.values(json);
console.log(arr);
Output:
['aa', 'cc']

Can you pass an array of index numbers to the array push method instead of specifying each index in push specifically

I want to create a new 2D array from another 2D array retaining specific columns from the original array that are defined in a variable.
I have a working version that uses hardcoded values of which columns from the original array to retain but I need a version that uses a variable.
var data = [
[1,5,7,8,9,98,56],
[4,7,8,9,2,55,88],
[3,3,4,3,3,24,11]
];
var indexes2Keep = [0,2,6];
data.forEach(function(row) {
slicedData.push( [ row[2], row[4], row[6] ] );
});
Instead of having the columns hardcoded in the array push method how can I use the values of the variable indexes2Keep to give the same result.
thanks
Expected output is:
slicedData = [
[1,7,56],
[4,8,88],
[3,4,11]
];

You can use Array.map/Array.filter:
var data = [
[1,5,7,8,9,98,56],
[4,7,8,9,2,55,88],
[3,3,4,3,3,24,11]
];
var indexes2Keep = [0,2,6];
var slicedData = data.map(function (row){
return row.filter(function(_,i){
return indexes2Keep.indexOf(i) !== -1
})
})
//Alternatively
var slicedData2 = data.map(function (row){
return indexes2Keep.map(function(i){
return row[i]
})
})
console.log(slicedData)
console.log(slicedData2)

Simply call .map on that array to map each index to the element at that index in the row.
data.forEach(function(row) {
slicedData.push(indexes2Keep.map(function(index) {return row[index]}));
});

You could use the map() function for this:
slicedData.push(indexes2Keep.map(index => row[index]));

How to convert a string version of a number array in json to a number array in javascript

I have the following json object:
var data = [{"name":"abc", "count":"[20.8, 100]"},
{"name":"xyz", "count":"[40, 100]"}]
Notice the array in double quotes : "[20.8, 100]"
I want the double quotes to go
Expected Output:
var data = [{"name":"abc", "count":[20.8, 100]},
{"name":"xyz", "count":[40, 100]}]
Any help would be appreciated

You could use JSON.parse and assign the value to the same property.
var data = [{"name":"abc", "count":"[20.8, 100]"}, {"name":"xyz", "count":"[40, 100]"}];
data.forEach(function (a) {
a.count = JSON.parse(a.count);
});
console.log(data);

Step 1 : Iterate the JSON using javaScript for...in loop.
Step 2 : Use JSON.parse() to convert the JSON string("[20.8, 100]") into JSON object([20.8, 100]).
Working demo :
var data = [
{"name":"abc", "count":"[20.8, 100]"},
{"name":"xyz", "count":"[40, 100]"}
];
for (var i in data) {
data[i].count = JSON.parse(data[i].count);
}
console.log(data);