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JavaScript JavaScript Array Iteration Methods Combining Array Methods Combining filter() and map()

Posted by Zach Freitag
Zach Freitag
20,341 Points

Using the filter and map methods on the todos array, create an array of unfinished task strings. - I'm lost..

I have tried:

unfinishedTask = todos
  .filter( todo => `${todo.done} == false`)
  .map(todo => ({todo}));

console.log(unfinishedTask);

// Returns every todo item - True & False.

I also tried:

unfinishedTask = todos
  .filter( todo => `${todo.done = false}`)
  .map(todo => ({todo}));

console.log(unfinishedTask);

// Returns every todo item - with their values changed to false.

I've tried a handful of other stuff with !== true and I'm getting nowhere.

Points go to best answer =)

Cheers!

app.js 
const todos = [
    {
        todo: 'Buy apples',
        done: false
    },
    {
        todo: 'Wash car',
        done: true
    },
    {
        todo: 'Write web app',
        done: false
    },
    {
        todo: 'Read MDN page on JavaScript arrays',
        done: true
    },
    {
        todo: 'Call mom',
        done: false
    }
];
let unfinishedTasks;

// unfinishedTasks should be: ["Buy apples", "Write web app", "Call mom"]
// Write your code below
unfinishedTask = todos
  .filter(todo => `${todo.done}` == false)
  .map(todo =>`${todo.todo}`);

5 Answers

Stuart Wright
Stuart Wright
41,120 Points

There's no need to use the template literal syntax here. Also note that you missed the s of the end of your new variable. Correct solution is:

unfinishedTasks = todos
  .filter(todo => todo.done === false)
  .map(todo => todo.todo);
Zach Freitag
Zach Freitag
20,341 Points

Thanks a ton Stuart!

I was trying to put everything together from all the videos leading up to this challenge and I thought this situation could be solved with template literals but less is more =)

Cheers!

Matthew Turner
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Matthew Turner
Full Stack JavaScript Techdegree Graduate 16,968 Points
Matthew Turner
.a{fill-rule:evenodd;}techdegree seal-36
Matthew Turner
Full Stack JavaScript Techdegree Graduate 16,968 Points

I am not sure why the following isn't working? I tried in my console and it works just fine. Am I missing something?

unfinishedTasks = todos
  .filter(todo => !todo.done)
  .map(todo => `${todo.todo}`);
janipalomino
janipalomino
510 Points

Because you don't need to use a template literal (interpolation) on your .map todo.

Nnanna Okoli
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Nnanna Okoli
Front End Web Development Techdegree Graduate 19,181 Points
Nnanna Okoli
.a{fill-rule:evenodd;}techdegree seal-36
Nnanna Okoli
Front End Web Development Techdegree Graduate 19,181 Points

I was so close .. I wrote this below

unfinishedTasks = todos 
    .filter(todo => todo.done === false)
    .map(todo => todo);
Ivonne Benites
Ivonne Benites
6,044 Points
Ivonne Benites
Ivonne Benites
6,044 Points

Dear everybody, Good afternoon

If someone please can explain me why in the solution part where the map is placed we refer only to todo.todo ?

unfinishedTasks = todos .filter(todo => todo.done === false) .map(todo => todo.todo);

David Shulkin
.a{fill-rule:evenodd;}techdegree
David Shulkin
Front End Web Development Techdegree Student 10,255 Points

the .todo appended to todos is the objects property value which are the strings

David Shulkin
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.a{fill-rule:evenodd;}techdegree
David Shulkin
Front End Web Development Techdegree Student 10,255 Points
David Shulkin
.a{fill-rule:evenodd;}techdegree
David Shulkin
Front End Web Development Techdegree Student 10,255 Points

Here I am filtering through the todos array returning 'done' tasks whose value is false. Next I map over the false todos and store them in the variable 'unfinshedTasks'

const unfinishedTasks = todos
    .filter(task => task.done != true)
    .map(task => task.todo)

You can also console.log() it when testing your code .map(task => console.log(task.todo))