1. truthy and falsy
all numbers are other than 0. and all strings are true other than an empty string. undefined is falsy. null, NaN, false is falsy value. after that, all numbers are true values and all strings true values and true is true value. white space is a truth value an empty object and an empty array is a truth value.
2. null VS undefined
we can take undefined value in some systems. first of all, we can set an undefined then we can get an undefined value and we can call object property but this property not uses then we can get undefined. and when…
1. React
react is building a user interface. and this is a javascript library. it's not a framework. the framework is a complete solution but the library is not a complete solution. after that library is best because when what you want and then that item is implemented in the library.
2. React JSX
JSX is HTML write formate. its uses by react. when we write HTML in react then that looks like HTML but it's not HTML. its a JSX or javascript XML. react JSX always convert to pure javascript then the browser engine read this code and show the UIs.
3. React’s tree reconciliation
when we write…
1. javaScript data type
the javascript data type is two types. primitive value and object and function. primitive types are 9 separate. number, string, boolean, object, function, etc. some are rarely used.
the null and undefined value is lonely. and every time you can find out every number, string boolean or etc. uses by javascript console. example: consol.log(typeof(2)) // number, consol.log(typeof(‘hello’)) // string.
2. error handle try…catch
every programmer should know to try and catch or error handling. if the client wrong input or programmer code mistake then this mistake handles the catch block. otherwise, try block run the code. when try block running when catch block ignored…
String :
1. String.prototype.charAt()
charAt() return new string. and this default value is the index(0). The first index position is 0, you will know string position then you will call charAt() method. and pass the index number. The first string position of 0, the second is index 1, the third string is index 2. this is charAt() method work.
EXAMPLE:
const sentence = ‘Learning with programming hero’;
console.log(`learning with programming hero, first index is: ${sentence.charAt(0)}`);
// expected output: “learning with programming hero, first index is: L”
2. String.prototype.concat()
concat() method return a new string. concatenates string argument calling to a new string. …
