Resolve: Uncaught TypeError: firebase.database is not a function

If you are getting the error: Uncaught TypeError: firebase.database is not a function
Resolve it by including firebase-database.js in your html page as follows:

<!-- The core Firebase JS SDK is always required and must be listed first -->
<script defer src="https://www.gstatic.com/firebasejs/6.2.4/firebase-app.js"></script>
<script defer src="https://www.gstatic.com/firebasejs/3.1.0/firebase-database.js"></script>

That is it. Let me know if this was helpful.

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

🐍 Advance List List is widely used and it's functionalities are heavily useful. Append Adds one element at the end of the list. Syntax list1.append(value) Input l1 = [1, 2, 3] l1.append(4) l1 Output [1, 2, 3, 4] append can be used to add any datatype in a list. It can even add list inside list. Caution: Append does not return anything. It just appends the list. Count .count(value) counts the number of occurrences of an element in the list. Syntax list1.count(value) Input l1 = [1, 2, 3, 4, 3] l1.count(3) Output 2 It returns 0 if the value is not found in the list. Extend .count(value) counts the number of occurrences of an element in the list. Syntax list1.extend(list) Input l1 = [1, 2, 3] l1.extend([4, 5]) Output [1, 2, 3, 4, 5] If we use append, entire list will be added to the first list like one element. Extend, i nstead of considering a list as one element, it joins the two lists one after other. Append works in the following way. Input l1 = [1, 2, 3] l1.append([4, 5]) Output...

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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