I am practicing ES6 on freeCodeCamp. Currently, I am solving a problem related to topic Template Literals. The problem statement is like
Use template literal syntax with backticks to display each entry of the result object's failure array. Each entry should be wrapped inside a li element with the class attribute text-warning, and listed within the resultDisplayArray.
After executing the code all test cases are passed except one
Template strings were used
and I am getting the error
Invalid regular expression flags
Please see below code and tell me where I am doing wrong.
const result = {
success: ["max-length", "no-amd", "prefer-arrow-functions"],
failure: ["no-var", "var-on-top", "linebreak"],
skipped: ["id-blacklist", "no-dup-keys"]
};
function makeList(arr) {
"use strict";
// change code below this line
const resultDisplayArray = arr.map(value =>
`<li class="text-warning">${value}</li>`);
// change code above this line
return resultDisplayArray;
}
/**
* makeList(result.failure) should return:
* [ <li class="text-warning">no-var</li>,
* <li class="text-warning">var-on-top</li>,
* <li class="text-warning">linebreak</li> ]
**/
const resultDisplayArray = makeList(result.failure);
Your code is correct and clear!
It is a bug at freeCodeCamp as you can see on this GitHub thread.
Cheers
Related
In WebhookScript, I can store a function in a variable with:
sub = function(a, b) {
return a - b
}
I'd like to store a function in a Global Variable so that I can use it in multiple Custom Actions. But if I've saved the above function as $sub$ then
sub2 = var('$sub$')
subX = sub(1,2)
causes an error:
Trying to invoke a non-function 'string' # line...
And
function subX(a,b){
var('$sub$')
}
when sub only contains return a - b, doesn't work either.
Obviously I need to convert the string to a function but I'm not sure whether that's possible.
I know this is a bit of an obscure language but if anyone knows how this can be done in similar languages like JavaScript and PHP, I'm happy to test out any guesses...
The solution here is to remove the function section and just enter the script, which inherits the execution scope so if my global variable $script$ is:
return 'hello ' + a
Then I can execute the function with:
a = 'world'
value = exec(var('$script$'))
echo(value)
(credit to Webhook.Site's support team for explaining this)
project im working on used es6/jsx and the airbnb linter but im having some trouble with the following code: i need to map items and compare it to another id but when i write it like this i get an error on the if statement, which is "parsing error unexpected token".
tried parentheses around the item, brackets after fat arrow, but not sure what the issue is. dont need to add return since it knows to expect it back. trying to find the way to get this working with the correct syntax.
const cartItems = items.map(item => {
if (id === item._id) {
console.log('found', item_id);
}
});
edit:
doing it like that, the .map(item has an error: expected parentheses around arrow function having curly braces.
moving over the => { i get an error: expected to return a value in arrow function
and in the console.log the item_id has a error: item._id is not defined, it should have been defined with the map but seems its not seeing it?
basically need to loop through the items id's and match them against another set of ids, if they match i need to combine the matching ones into a new variable
Ive changed it a bit, for what i need by doing it like this:
if (id === items.map(item => item._id)) {
this.setState({ inCart: true });
}
then just use the state value to conditionally load anything i needed.
I am trying to add a function to my Conky which prints the length of a string for debug purposes. The code, inside a file called test.lua, is pretty trivial:
function test(word)
return string.len(word)
end
...and I load it like this. In my conky.config section I have:
lua_load = '/home/xvlaze/test.lua',
lua_draw_hook_pre = 'test'
...in the conky.text section I have:
${lua test "fooo"}
...where test is the name of the function and fooo the string to test.
The expected result should be a printed 4 in Conky, but instead of that I get:
conky: llua_do_call: function conky_test execution failed: /home/xvlaze/test.lua:2: attempt to index a nil value (local 'string')
conky: llua_getstring: function conky_test didn't return a string, result discarded
I have browsed through the documentation, but I can't find anything. Does anybody know where the failure is?
Several guidances on how to implement functions in Conky:
First of all: YOU MUST USE conky_ BEFORE YOUR FUNCTION'S NAME.
Otherwise, you will get the following error when running your Conky:
attempt to call a nil value
Secondly: YOU MUST ALWAYS RETURN A VALUE.
I don't mind repeating it - it is crucial. Otherwise, you will get:
function foobar didn't return a string, result discarded
function_result
...in your terminal, and your Conky will be left empty of values related to your extra code. Nothing will be printed regarding your function.
Last but not least: YOU MUST ALWAYS CALL YOUR FUNCTION LIKE:
lua_load = '/path/to/function.lua',
-- Whatever content...
${lua function_name function_parameter1 function_parameterN} -- In case you use more than one parameter.
In summary, a dummy function template could be:
MAIN FILE (conky.conf):
conky.config = {
-- Whatever content... Lua styled comments.
lua_load = '/path/to/function.lua',
}
conky.text = [[
# Whatever content... In this section comments are started with '#'!
${lua function_name parameter}
]]
FUNCTION FILE:
function conky_function_name(parameter)
-- Whatever content... Remember this is Lua, not conky.text syntax. Always use '--' comments!
return whatever -- No return, no party. A function MUST always return something!
end
This is my first cut:
const planLimits = {plan1: {condition1: 50, ...}}
function initialisePlanLimits(planLimits) {
const limits = new Map();
Object.keys(planLimits).map((planId) => (
const limitMap = new Map(Object.entries(planLimits[planId]));
limits.set(planId, limitMap);
));
return limits;
}
The linter flags this error: error Expected to return a value in this function array-callback-return
So I changed to this version:
function initialisePlanLimits(planLimits) {
const limits = new Map();
Object.keys(planLimits).map((planId) => (
limits.set(planId, new Map(Object.entries(planLimits[planId])))
));
return limits;
}
It throws another error Unexpected parentheses around single function argument having a body with no curly braces arrow-parens
My questions:
1) I reckon I can fix my first version by sticking in a return null within the curry bracket. But is there a better, more elegant way? A bogus return statement does not make sense in this context
2) Why the second version fails? Isn't it equivalent to the first version?
If I use forEach instead of map, it will not cause the array-callback-return lint error
Object.keys(planLimits).forEach((planId) => (
const limitMap = new Map(Object.entries(planLimits[planId]));
limits.set(planId, limitMap);
));
Well, accepted answer advocates about using 'forEach,' which is true. Please read below explaination from ESLint documentation,
Array has several methods for filtering, mapping, and folding. If we forget to write return statement in a callback of those, it's probably a mistake. If you don't want to use a return or don't need the returned results, consider using .forEach instead.
TLDR: ESLint and Function Return Values
This issue is caused by not returning a value when using map(), see how the results are expected according to the docs...
The map() method creates a new array populated with the results of calling a provided function on every element in the calling array. (Source: MDN WebDocs.)
Demonstration of Issue in JavaScript
With this code sample of JS, which shows a group of elements...
var newarray = [];
array.map( (item, index) => {
newarray.push('<li>' + item + '</li>');
});
I get this error...
Expected to return a value in arrow function array-callback-return
The error goes away if I add a single return to the above function, like so :
var newarray = array.map( (item, index) => {
return '<li>' + item + '</li>';
});
`map()` - So why should I use it?
You can clearly see elsewhere, too, on MDN Docs, that what is returned is, "A new array with each element being the result of the [return value of the] callback function." So, if you are using map(), it's also a very good idea to also use return returnvalue!
map() is a powerful tool. Don't throw that tool away.
I'm working with lua-alchemy, and I'm setting a global variable in my AS3 code in this way:
_lua.setGlobal("map", _map);
With _map being a object with the following function in it:
public function get x():int
{
return 10;
}
if then I try to do something like this in Lua
local a = map.x + 1
I get the following error:
Lua script failed: luaDoString:21: attempt to perform arithmetic on field 'x' (a table value)
Does anyone knows why it does that, and how I could fix it?
EDIT :
When I print type(map.id), it prints table... Shouldn't it print number?
I found my error. According to this page, I have to use as3.tolua(map.x) to convert it to the right type.