Q731. 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...
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Q732. How to create props proxy for HOC component?
You can add/edit props passed to the component using _props proxy_ pattern like this: ```jsx harmony function HOC(WrappedComponent) { return class Test extends Component ...
Q733. How do you map the array values without using map method?
You can map the array values without using the `map` method by just using the `from` method of Array. Let's map city names from Countries array, ```javascript const count...
Q734. What is context?
_Context_ provides a way to pass data through the component tree without having to pass props down manually at every level. For example, authenticated users, locale prefe...
Q735. How do you empty an array?
You can empty an array quickly by setting the array length to zero. ```javascript let cities = ["Singapore", "Delhi", "London"]; cities.length = 0; // cities becomes [] `...
Q736. What is the purpose of using super constructor with props argument?
A child class constructor cannot make use of `this` reference until the `super()` method has been called. The same applies to ES6 sub-classes as well. The main reason for...
Q737. How do you round numbers to certain decimals?
You can round numbers to a certain number of decimals using `toFixed` method from native javascript. ```javascript let pie = 3.141592653; pie = pie.toFixed(3); // 3.142 `...
Q738. How to set state with a dynamic key name?
If you are using ES6 or the Babel transpiler to transform your JSX code then you can accomplish this with _computed property names_. ```javascript handleInputChange(event...
Q739. What is the easiest way to convert an array to an object?
You can convert an array to an object with the same data using spread(...) operator. ```javascript var fruits = ["banana", "apple", "orange", "watermelon"]; var fruitsObj...
Q740. What would be the common mistake of function being called every time the component renders?
You need to make sure that function is not being called while passing the function as a parameter. ```jsx harmony render() { // Wrong: handleClick is called instead of pa...