JS - Which array method to use?

Array built-in object documentation

To mutate original array

Add to original

• .push() (end)
• .unshift() (start)

Remove from original

• .pop() (end)
• .shift() (start)
• .splice() (any)

Others

• .reverse()
• .sort()
• .fill

A new array

Computed from original

• .map() (loop)

Filtered using condition

• .filter()

Portion of original

• .slice()

Adding original to other

• .concat()

Flattening the original

• .flat()
• .flatMap()

An array index

Based on value

• .indexOf()

Based on test condition

• .findIndex()

An array element

Based on test condition

• .find()

Know if array includes

Based on value

• .includes()

Based on test condition

• .some()
• .every()

A new string

Based on separator string

• .join()

To transform to value

Based on accumulator

• .reduce()

To just loop array

Based on callback

• .forEach()