React: trigger onChange if input value is changing by state?

Edit: I don’t want to call handleChange only if the button has been clicked. It has nothing to do with handleClick. I gave an example in the @shubhakhatri answer’s comment. I want to change the input value according to state, the value is changing but it doesn’t trigger handleChange() method. How can I trigger handleChange() method ? Here is the … Read more

Node.js – SyntaxError: Unexpected token import

Node 13+ Since Node 13, you can use either the .mjs extension, or set {“type”: “module”} in your package.json. You don’t need to use the –experimental-modules flag. Modules is now marked as stable in node.js Node 12 Since Node 12, you can use either the .mjs extension, or set “type”: “module” in your package.json. And you need to run node with the –experimental-modules flag. Node 9 In Node 9, it is enabled behind a flag, and … Read more

What is the ‘new’ keyword in JavaScript?

It does 5 things: It creates a new object. The type of this object is simply object. It sets this new object’s internal, inaccessible, [[prototype]] (i.e. __proto__) property to be the constructor function’s external, accessible, prototype object (every function object automatically has a prototype property). It makes the this variable point to the newly created object. It executes the constructor function, using the newly created … Read more

What’s the best way to convert a number to a string in JavaScript?

like this: Actually, even though I typically do it like this for simple convenience, over 1,000s of iterations it appears for raw speed there is an advantage for .toString() See Performance tests here (not by me, but found when I went to write my own): http://jsben.ch/#/ghQYR Fastest based on the JSPerf test above: str = num.toString(); It should be … Read more

What does this symbol mean in JavaScript?

See the documentation on MDN about expressions and operators and statements. Basic keywords and general expressions this keyword: How does the “this” keyword work? var x = function() vs. function x() — Function declaration syntax var functionName = function() {} vs function functionName() {} (function(){…})() — IIFE (Immediately Invoked Function Expression) What is the purpose?, How is it called? Why does (function(){…})(); work but function(){…}(); doesn’t? (function(){…})(); vs (function(){…}()); shorter alternatives: !function(){…}(); – What … Read more

How to find the sum of an array of numbers

Recommended (reduce with default value) Array.prototype.reduce can be used to iterate through the array, adding the current element value to the sum of the previous element values.  Run code snippetExpand snippet Without default value You get a TypeError  Run code snippetExpand snippet Prior to ES6’s arrow functions  Run code snippetExpand snippet Non-number inputs If non-numbers are … Read more