What does a null mean in React.createElement()?

The null is React.createElement is reserved for giving attribute values to the element. If you have none to pass then you put in a null, else you pass the attribute in a javascript object form. See example below. Here className is used for class as that is what is used in jsx to define html class.

import React, { Component } from 'react';
import './App.css';


class App extends Component {
  render() {
    return React.createElement('div', { className: "App" }, React.createElement('h1', null,'Title'));
  }
}

export default App;

This example outputs <div class="App"><h1>Title</h1></div>

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Python - List - Append, Count, Extend, Index, Insert, Pop, Remove, Reverse, Sort

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Difference between .exec() and .execPopulate() in Mongoose?

Here I answer what is the difference between .exec() and .execPopulate() in Mongoose? .exec() is used with a query while .execPopulate() is used with a document Syntax for .exec() is as follows: Model.query() . populate ( 'field' ) . exec () // returns promise . then ( function ( document ) { console . log ( document ); }); Syntax for .execPopulate() is as follows: fetchedDocument . populate ( 'field' ) . execPopulate () // returns promise . then ( function ( document ) { console . log ( document ); }); When working with individual document use .execPopulate(), for model query use .exec(). Both returns a promise. One can do without .exec() or .execPopulate() but then has to pass a callback in populate.

683 K Empty Slots

Approach #1: Insert Into Sorted Structure [Accepted] Intuition Let's add flowers in the order they bloom. When each flower blooms, we check it's neighbors to see if they can satisfy the condition with the current flower. Algorithm We'll maintain active , a sorted data structure containing every flower that has currently bloomed. When we add a flower to active , we should check it's lower and higher neighbors. If some neighbor satisfies the condition, we know the condition occurred first on this day. Complexity Analysis Time Complexity (Java): O(N \log N) O ( N lo g N ) , where N N is the length of flowers . Every insertion and search is O(\log N) O ( lo g N ) . Time Complexity (Python): O(N^2) O ( N 2 ) . As above, except list.insert is O(N) O ( N ) . Space Complexity: O(N) O ( N ) , the size of active . Approach #2: Min Queue [Accepted] Intuition For each contiguous block ("window") of k po...

Vinit Khandelwal

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