bobbyhadz blog

To use a shorthand for an if else statement, use the ternary operator. The ternary operator starts with a condition that is followed by a question mark `?`, then a value to return ...

To format a date as yyyy-mm-dd hh:mm:ss get all the components of the date using the methods on the Date object. Add a leading zero to the day, month, hours, minutes and seconds if...

To resolve the `removeEventListener` not working issue, make sure to pass the same function to the `addEventListener` and `removeEventListener` methods. Passing a function that poi...

To remove the last comma from a string, call the `replace()` method with the following regular expression `/,*$/` as the first parameter and an empty string as the second. The `rep...

To push an element in an array if it doesn't exist, use the `includes()` method to check if the value exists in the array, and push the element if it's not already present. The `in...

To convert a string to a boolean, use the equality operator to compare the string to the string `true`, e.g. `const bool = str === 'true'`. If the condition is met, the strict equa...

To join non-empty strings with a separator, add the strings to an array and call the `filter()` method on the array to filter only for truthy values, e.g. `[str1, str2].filter(Bool...

The "Cannot set property which has only a getter" error occurs when trying to set a new value to a property, for which only a getter is defined. To solve the error, define a setter...

To check if all of the values in an object are equal, use the `Object.values()` method to get an array of the object's values and convert the array to a `Set`. If the `Set` contain...

To check if a value is an object check that the value has a type of object - `typeof variable === 'object'`. Then verify the value is not `null` - `variable !== null` and verify th...

To iterate over a `Set` in reverse order use the `Array.from()` method to convert the `Set` to array. Then use the `reverse()` method to reverse the array and call the `forEach` me...

To split a string by space or comma, pass the following regular expression to the `split()` method - `/[, ]+/`. The method will split the string on each occurrence of a space or co...

To convert all values in a `Set` to lowercase, create a second `Set`, that will store the lowercase values. Then use the `forEach` method to iterate over the first `Set` and on eac...

To split a string into substring on N characters, call the `match()` method on the string, passing it the following regular expression `/.{1, N}g/`. The `match` method will return ...

To swap the keys and values in an object, call the `Object.entries()` method to get an array of key-value pairs and use the `map()` method to switch the places of the key and the v...

To replace or remove characters that don't match a regex, call the `replace()` method on the string passing it a regular expression that uses the caret `^` symbol, e.g. `/[^a-z]+/`...

The reason the `map()` method returns undefined values is because we forget to explicitly return a value in the callback function we passed to the method.

Use the spread operator (...) to sort an array without mutating the original, e.g. `[...arr].sort()`. The spread operator creates a shallow copy of the original array, on which you...