zoukankan      html  css  js  c++  java
  • ES6 new syntax of Literal

    Object Literal Extensions.md

    var price = 4.20, quantity = 20;
    var invoiceData = {
        price: price,
        quantity: quantity
    };
    
    console.log(invoiceData);
    

    Declaring price and quantity twice is kind of redundant,but es6 provides a shorthand making writing this simpler.

    var price = 4.20, quantity = 20;
    var invoiceData = {
        price,
        quantity
    };
    
    console.log(invoiceData);
    

    ES6 also gives us a short notation to wirte functions in an object literal.

    const price = 4.20,quantity = 20;
    const invoiceData = {
        price,
        quantity,
        calculateTotal(){
            return this.price * this.quantity;
        }
    };
    
    console.log(invoiceData.calculateTotal());
    

    *In the above shorthand notation, you no longer need the keyword function.When we use the shorthand within an object literal, this refers to the context of the code just like an arrow funtion.It does not refer to the object that contains the function.It behaves exactly like an arrow function. *

    const field = "dynmicRandom";
    const price = 5.99;
    const quantity = 2;
    const invoiceData = {
        [field]:price,
        quantity,
        calculateTotal(){
            return this.price * this.quantity;
        }
    };
    
    console.log(invoiceData);
    

    const field = "dynmicRandom";
    const price = 5.99, quantity = 2;
    const invoiceData = {
        [field + "-01"]: price,
        quantity,
        calculateTotal(){
            return this.price * this.quantity;
        }
    };
    console.log(invoiceData);
    

    Template Literals and Delimiters

    ES6 Template Literals which provide you a way to defined strings with addational functionalities like
    String interpolation
    Embedded expressions
    Multiline strings without hacks
    String formatting

    let user = `Kevin`;
    console.log(`Hi ${user}!`);
    
    let a = 10;
    let b = 20;
    console.log(`Sum of ${a} and ${b} is ${a+b}`);
    
    console.log(`I am line one
        I am line two`);
    
    output `Hi, my name is ${name} and I love ${language}`;
    

    1.Array of literal strings, that is ["Hi,my name is ","and I love", ""]
    2.Substitutions,that is, name, language.

    output(["Hi,my name is", "and I love", ""],name, language)

    function output(literals, ...substitutions){
        let result= "";
        for(let i = 0 ;i < substitutions.length; i++) {
            result += literals[i] + substitutions[i];
        }
    
        result += literals[literals.length - 1];
        return result;
    }
    const name = "John",
        language = "Javascript";
    
        let text = output `Hi,my name is ${name} and I love {language}`
        console.log(text);
    

    Iterating with for...of

    let names = ['matt','smith','jack'];
    
    for(let i = 0; i<names.length; i++) {
        console.log(name[i]);
    }
    
    let names = ["matt", "smith", "jack"];
    
    for(let names of names){
        console.log(name);
    }
    
    for(let char of "Bye"){
        console.log(char);
    }
    
  • 相关阅读:
    HDU3107 Godfather(树的重心)
    POJ1655 Balancing Act(树的重心)
    codeforces 691F Couple Cover(暴力预处理)
    codeforces 691E Xor-sequences(矩阵快速幂)
    codeforces 691D Swaps in Permutation(并查集)
    HDU5727 Necklace(环排+匈牙利)
    codeforces679C Bear and Square Grid(dfs优化)
    codeforces679B Bear and Tower of Cubes(思路)
    spring boot
    spring boot资料收集
  • 原文地址:https://www.cnblogs.com/InnerPeace-Hecdi/p/8939656.html
Copyright © 2011-2022 走看看