In the ng-bootstrap modal documentation there are uses of some kind of let-* attribute that seemed to be used to link a function or event for later use. The main difference is that the scope of a var variable is the entire enclosing function: Variables can be declared using const similar to var or let declarations. let greeting = "say Hi"; let times = 4; if (times > 3) { let hello = "say Hello instead"; console.log(hello);//"say Hello instead" } console.log(hello) // hello is not defined We see that using hello outside its block(the curly braces where it was defined) returns an error. Examples Scoping rules. It’s not a replacement to var, var can still be used even in ES6 and has the same semantics as ES5. let gives you the privilege to declare variables that are limited in scope to the block, statement of expression unlike var. Thus, variables declared using let minimize the possibilities of runtime errors, as the compiler give compile-time errors. Variables declared by let have their scope in the block for which they are defined, as well as in any contained sub-blocks. var is rather a keyword which defines a variable globally regardless of block scope. Join the community of millions of developers who build compelling user interfaces with Angular. We use the const keyword initialize a constant whose value does not change. Angular is a platform for building mobile and desktop web applications. Review: Variable Declarations. Angular is a platform for building mobile and desktop web applications.

The data types We can use var , let , or const keywords when declare a variable. JavaScript: var vs. let. The const makes a variable a constant where its value cannot be changed. We will use very simple program to explain the difference between var vs let keywords in angular 2 typescript. Variables declared by let have their scope in the block for which they are defined, as well as in any contained sub-blocks. ‘var’ declaration was available since the beginning of JavaScript and let statement was recently introduced in the ES6 (ES 2015) version of JavaScript to enforce block scoping functionalities.

That statement emphasizes that let should replace var only when var was already signaling block scoping stylistically. Difference between VAR and LET Angular 2 September 23, 2017 by TestAccount Leave a Comment In this post we will see how var keyword in type script is different from let keyword. You must understand var to grasp the benefits of let / const.Let’s rewind. Just like let, const declarations are hoisted to the top but are not initialized.. Difference between VAR and LET Angular 2. However unless you have a specific reason to use var I would expect all variables you define from now on to use let. The let keyword declares a template input variable that you reference within the template. September 23, 2017 by TestAccount Leave a Comment. In this way, let works very much like var. If we do not explicitly specify the variable data-type ( for example name : string , mynum : number or isOk : boolean ), then TypeScript will automatically infer the type of a variable based on its value.
Join the community of millions of developers who build compelling user interfaces with Angular. This appears to be a feature of Angular and has nothing to do with ng-bootstrap. NO, let is the new block scoping var. In this way, let works very much like var. Const Declaration. const. This will update the value of greeting.message without returning errors.. Hoisting of const.

A Gentle Introduction to ES6. Otherwise, leave var alone. There is value in block scope for loops, but I can’t think of a situation where I’d prefer `var` over `let`. Use var and let to define any variable, with or without type or initial value.

Geschrieben: vor 5 Jahren von Matthias Kleine. Había una vez tres bandos en el mundo Typescript: var, let y const. We will use very simple program to explain the difference between var vs let keywords in angular 2 typescript. Mấy bài viết nói về 3 từ khóa này trong JavaScript thì có nhiều rồi, mình chỉ tổng hợp lại cho ngắn để các bạn lười đọc tham khảo nhanh thôi .