What does .map() return? The .map() function in JavaScript returns a new array populated with the results of calling a provided function on every element in the calling array.
If I want to loop through an array and display each value in JSX, how do I do that in React? You can use the .map() function inside curly braces {} in JSX to iterate through an array and display each value.
Each list item needs a unique ____. Each list item in React needs a unique key prop.
What is the purpose of a key? The purpose of a key in React is to help React identify which items have changed, are added, or are removed. It helps optimize the rendering process by providing a stable identity to elements, especially when dealing with lists.
What is the spread operator?* The spread operator (...) is a syntax in JavaScript used for expanding elements of an iterable (like arrays, objects, strings) into places where multiple elements are expected.
List 4 things that the spread operator can do.
- Combine arrays
- Copy arrays
- Merge objects
- Pass elements of an iterable as function arguments
Give an example of using the spread operator to combine two arrays. const array1 = [1, 2, 3]; const array2 = [4, 5, 6]; const combinedArray = [...array1, ...array2]; console.log(combinedArray);
Give an example of using the spread operator to combine two objects into one. const oldArray = [1, 2, 3]; const newItem = 4; const newArray = [...oldArray, newItem]; console.log(newArray);
Give an example of using the spread operator to combine two objects into one. const obj1 = { a: 1, b: 2 }; const obj2 = { c: 3, d: 4 }; const combinedObj = { ...obj1, ...obj2 }; console.log(combinedObj);
what is the first step that the developer does to pass functions between components? They defined the function in the parent component
In your own words, what does the handleClick function do? The handleClick function is like a special action button in React. It's a function that runs when something specific happens, like when you click on something in the app. Its job is to decide what should happen next after that click.
How can you pass a method from a parent component into a child component? You can pass a method from a parent component to a child component by defining the method in the parent component and then passing it down to the child component as a prop. This allows the child component to access and invoke the method.
How does the child component invoke a method that was passed to it from a parent component? The child component can invoke a method that was passed to it from a parent component by simply calling the method as a function within the child component. Since the method is passed as a prop, it is accessible within the child component, and invoking it will execute the function defined in the parent component.