value questions

`Array.prototype.fill` fills all the elements of an array from a specified start index to an end index with a static value. It modifies the original array and returns the updated array. 

const arr = [1, 2, 3, 4];
arr.fill(0, 1, 3);
console.log(arr); // [1, 0, 0, 4]

`Array.prototype.fill` fills all elements of an array from a start index to an end index with a static value. It modifies the original array and returns the updated array. 

const arr = [1, 2, 3, 4];
arr.fill(0, 1, 3);
console.log(arr); // [1, 0, 0, 4]

`Array.isArray` determines whether a value is an array. It returns `true` if the value is an array, otherwise `false`. 

console.log(Array.isArray([1, 2, 3])); // true
console.log(Array.isArray({})); // false

`Array.prototype.entries` returns a new Array Iterator object that contains the key/value pairs for each index in the array. It allows iteration over the array's indices and values. 

const arr = ['a', 'b', 'c'];
const iterator = arr.entries();
for (const [index, element] of iterator) {
  console.log(index, element);
}
// Output:
// 0 'a'
// 1 'b'
// 2 'c'

`Array.prototype.values` returns a new Array Iterator object that contains the values for each index in the array. It allows iteration over the array's values. 

const arr = ['a', 'b', 'c'];
const iterator = arr.values();
for (const value of iterator) {
  console.log(value);
}
// Output:
// 'a'
// 'b'
// 'c'

`Array.prototype.reduce` executes a reducer function on each element of the array, accumulating a single result. It takes a callback function and an optional initial value, and returns the final accumulated result. 

const arr = [1, 2, 3];
const sum = arr.reduce((acc, num) => acc + num, 0);
console.log(sum); // 6

`Array.prototype.includes` determines whether an array contains a certain value among its entries. It returns `true` if the array contains the value, otherwise `false`. 

const arr = [1, 2, 3];
console.log(arr.includes(2)); // true
console.log(arr.includes(4)); // false

`Array.prototype.fill` changes all elements in an array to a static value from a start index to an end index. It modifies the original array. 

const arr = [1, 2, 3];
arr.fill(0, 1, 3);
console.log(arr); // [1, 0, 0]

`String.prototype.toUpperCase` returns a new string with all characters converted to uppercase. 

const str = 'hello';
const upper = str.toUpperCase();
console.log(upper); // 'HELLO'

`String.prototype.toLowerCase` returns a new string with all characters converted to lowercase. 

const str = 'HELLO';
const lower = str.toLowerCase();
console.log(lower); // 'hello'

`String.prototype.indexOf` returns the index of the first occurrence of a specified value in a string. If the value is not found, it returns -1. 

const str = 'hello';
const index = str.indexOf('l');
console.log(index); // 2

useDeferredValue allows deferring updates to non-urgent state changes, making the UI more responsive. It works by deferring the rendering of less important updates, allowing more critical updates to be processed first, thus improving overall performance.

The VALUE function converts text that represents a number into a numeric value. For example, =VALUE('1234') converts the text '1234' into the number 1234. This function is useful when working with text values that need to be used in numerical calculations.

The INDEX function returns the value of a cell in a specified row and column within a range. For example, =INDEX(A1:C10, 2, 3) returns the value from the second row and third column in the range A1:C10. This function is useful for retrieving specific data points from a table.

The CEILING function rounds a number up to the nearest multiple of a specified value. For example, =CEILING(5.3, 1) returns 6, as it rounds 5.3 up to the nearest whole number. This function is useful for rounding numbers in financial and statistical calculations.

The FLOOR function rounds a number down to the nearest multiple of a specified value. For example, =FLOOR(5.7, 1) returns 5, as it rounds 5.7 down to the nearest whole number. This function is useful for financial and statistical calculations requiring rounding down.

The NOT function reverses the logical value of its argument. For example, =NOT(A1>10) returns TRUE if A1 is not greater than 10, and FALSE if A1 is greater than 10. This function is useful for negating conditions in logical tests.

The VLOOKUP function searches for a value in the first column of a table and returns a value from a specified column in the same row. For example, =VLOOKUP('Apple', A1:C10, 2, FALSE) searches for 'Apple' in column A and returns the corresponding value from column B. This function is useful for looking up information in tables.

The IFERROR function returns a specified value if a formula results in an error; otherwise, it returns the result of the formula. For example, =IFERROR(A1/B1, 'Error') returns 'Error' if dividing A1 by B1 results in an error, otherwise it returns the division result. This function is useful for handling potential errors in calculations.

The LOOKUP function searches for a value in one row or column and returns a value from the same position in a second row or column. For example, =LOOKUP(10, A1:A10, B1:B10) looks for the number 10 in A1:A10 and returns the corresponding value from B1:B10. This function is useful for simple lookups and data retrieval.

To sum values across multiple sheets, use a formula like =SUM(Sheet1:Sheet3!A1) which sums the values in cell A1 across Sheet1, Sheet2, and Sheet3. This method is useful for aggregating data from multiple sheets into a single total.

The Context API in React Native allows you to pass data through the component tree without having to pass props manually at every level. You create a Context object using `React.createContext`, and then use `Provider` and `Consumer` components to manage and access the context data. This is useful for global state management and theme handling.

An Invalid Path Variable error occurs when a path variable in a URL does not match the expected format or value. Verify that path variables are correctly formatted and correspond to the expected values in routing configurations. Implement validation to ensure that variables meet expected criteria.