Q611. How to pass a parameter to an event handler or callback?
You can use an _arrow function_ to wrap around an _event handler_ and pass parameters: ```jsx harmony this.handleClick(id)} /> ``` This is an equivalent to calling `.bind...
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Q612. What is the difference between reflow and repaint?
A _repaint_ occurs when changes are made which affect the visibility of an element, but not its layout. Examples of this include outline, visibility, or background color....
Q613. What happens with negating an array?
Negating an array with `!` character will coerce the array into a boolean. Since Arrays are considered to be truthy So negating it will return `false`. ```javascript cons...
Q614. What happens if we add two arrays?
If you add two arrays together, it will convert them both to strings and concatenate them. For example, the result of adding arrays would be as below, ```javascript conso...
Q615. What are forward refs?
_Ref forwarding_ is a feature that lets some components take a _ref_ they receive, and pass it further down to a child. ```jsx harmony const ButtonElement = React.forward...
Q616. What is the output of prepend additive operator on falsy values?
If you prepend the additive(+) operator on falsy values(null, undefined, NaN, false, ""), the falsy value converts to a number value zero. Let's display them on browser c...
Q617. How do you create self string using special characters?
The self string can be formed with the combination of `[]()!+` characters. You need to remember the below conventions to achieve this pattern. 1. Since Arrays are truthfu...
Q618. How do you remove falsy values from an array?
You can apply the filter method on the array by passing Boolean as a parameter. This way it removes all falsy values(0, undefined, null, false and "") from the array. ```...
Q619. How do you get unique values of an array?
You can get unique values of an array with the combination of `Set` and rest expression/spread(...) syntax. ```javascript console.log([...new Set([1, 2, 4, 4, 3])]); // [...
Q620. What is destructuring aliases?
Sometimes you would like to have a destructured variable with a different name than the property name. In that case, you'll use a `: newName` to specify a name for the va...