Teh Codez

Question 1

Webpack solves which fundamental problem?

Answer 1

bundling

Question 2

What is the difference between /usr/bin and /usr/local/bin

Answer 2

/usr/local/bin is for locally compiled packages which upgrades may modify or delete without warning. /usr/bin is for distribution-managed programs.

Question 3

Why use Webpack over a task runner such as Grunt or Gulp?

Answer 3

Webpack does all the preprocessing for you, and gives specified bundles based on configuration and the existing code.

Question 4

npm: what is the difference between dependencies and devDependencies?

Answer 4

devDependencies are not installed in a directory with package.json with the –production flag. In other direcctories, they are not installed without the –dev flag. devDependencies are not installed transitively.

Question 5

What is a source map?

Answer 5

A source map consists of information that can be used to map a compressed file back to its original sources.

Question 6

Name several special characters in HTML.

Answer 6

& code ;

Question 7

The shell: how do you go to the beginning of a line? To the end of the line? Delete everything right of the cursor?

Answer 7

CTRL-A, CTRL-E, CTRL-K

Question 8

How do you provide a default file name for a downloaded file?

Answer 8

Place the name of the file in the download attribute.

Question 9

What is a webpack loader?

Answer 9

A webpack loader is the equivalent of a task in most task runners. It preprocesses files as they are required.

Question 10

How do you enforce order with webpack loaders?

Answer 10

Either use them right to left, bottom to top, or use the enforce flag in the rules, setting it either to pre or post.

Question 11

Name two ways of passing parameters to loaders. Which is preferred?

Answer 11

Inline, and using the options object within the module rules. Options is preferred due to readability.

Question 12

In webpack, how can you use more than one loader?

Answer 12

Place separate loader configurations in the use array.

Question 13

Name at least four ways to blockquote HTML using tags.

Answer 13

blockquote, code, q, cite,

Question 14

Name five tags for representing computer code.

Answer 14

code, pre, var , kbd, samp

Question 15

What HTML tag is used to markup times and dates?

Answer 15

Use the time tag with the datetime attribute.

Question 16

Describe how React’s event handling differs from HTML’s syntactically.

Answer 16

HTML inline will list the event in lower case, and set the event to the name of the method, with parentheses, between quotes. React will list the event inline to the name of the method, camelCase, between curly braces.

Question 17

Can you return false to prevent default behavior in React?

Answer 17

No, you must call preventDefault explicitly.

Question 18

What does the JavaScript bind() method do?

Answer 18

It creates a new function with the this keyword set to the provided value. If any other arguments are provided, they appear first in the new function. Habitually use bind whenever you refer to a method without () after it.

Question 19

True or false: in JavaScript, class methods are bound by default.

Answer 19

False.

Question 20

In React, how do you prevent a component from rendering?

Answer 20

return null

Question 21

In React, describe a way you can conditionally render an element.

Answer 21

In curly brackets, use an expression with the && operator. The rhs will only render if the lhs is true.

Question 22

Describe JavaScript’s map function.

Answer 22

An array function, it returns a transformed array by taking a callback which has three arguments, an array element, the array index, and a reference to the initial array. The return value of the callback is the updated array element. The initial array is unchanged unless the developer explicitly changes it.

Question 23

Describe JavaScript’s filter function.

Answer 23

An array function, it returns values that return true for a given condition. It takes a callback and passes in three arguments, an array element, an index, and a reference to the initial array.

Question 24

Describe JavaScript’s reduce function.

Answer 24

An array function, it takes a callback that has four arguments, and an initial value. The callback takes an accumulator, the current array value, the current index, and a reference to the initial array. When the initial value is not given, the accumulator defaults to the first value of the array.

Question 25

How do you give React list elements a stable identity?

Answer 25

Among siblings, provide a unique key. If there is any ambiguity, make sure they’re on the component, not on the element.

Question 26

What two attributes should be set on a form tag?

Answer 26

action, where the form data will be sent, and method, which should be either get or post.

Question 27

What attribute is on the label tag?

Answer 27

for. It links the label to a widget by specifying the widget id.

Question 28

What possible three values may the type attribute of a button tag have?

Answer 28

submit, reset, button. Reset should not be used. Submit sends the data to the endpoint specified in the action attribute. button is useful for building custom JavaScript buttons.

Question 29

Why should form inputs have a name attribute?

Answer 29

The server needs a way to identify the data sent.

Question 30

What is a controlled React component?

Answer 30

A component whose state is tied to React’s state. For example, a user enters an input, onChange is called, setState is invoked. Every state mutation has a handler function.

Question 31

What makes a React textarea different?

Answer 31

It is written with a single tag, and uses a value attribute like an ordinary input for its value.

Question 32

What makes a React select element different?

Answer 32

A React select element uses a value on the select tag to identify the selected option, rather than placing a selected attribute directly on the option tag.

Question 33

In JavaScript, how do you create an object with properties, using the variable names as keys?

Answer 33

Use the es6 shorthand. Entering variables alone within curly braces is all the needed syntax.

Question 34

In JavaScript, what is the most elegant notation for adding object functions?

Answer 34

Inside the object definition, use the function name, arguments, and definition. In es6, no anonymous functions or property labels are required.

Question 35

In JavaScript, what is a computed property name?

Answer 35

Array brackets will compute the value between them when followed by a colon, when inside an object.

Question 36

In React, what is lifting state up?

Answer 36

When two components share a state, it should be moved up to the closest common ancestor.

Question 37

In React, a component does not know its children ahead of time. What do?

Answer 37

Pass them as children, render them as props.children.

Question 38

When building an initial static version of a React app, should you use props? Should you use state?

Answer 38

Use props. Do not use state. State is needed for interactivity, that is, data that changes over time.

Question 39

Why use Redux?

Answer 39

As a React project gets large, the front end should not know about the business logic. Redux gives each React component the exact piece of state it needs.

Question 40

How do you avoid mutations in Redux?

Answer 40

Use concat(), slice(), and …spread for arrays. Use Object.assign() and …spread() for objects.

Question 41

How do you get the object spread operator?

Answer 41

npm the babel-plugin-transform-object-rest-spread package, and update the babel configuration. transform-object-rest-spread should be in the plugins.

Question 42

Name a major gotcha when using morgan middleware for Express.

Answer 42

morgan must be used before routes are used, not after.

Question 43

Name a major gotcha when using Winston with express.

Answer 43

Be sure to use the full path using __dirname when setting up a transport.

Question 44

In express, when shouldn’t you use compression middleware?

Answer 44

Don’t use compression middleware when you have a reverse proxy.

Question 45

How do you see the git history?

Answer 45

git log