Javascript 如何在Typescript中连接字符串和数字
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How to concat string and number in Typescript
提问by Anna F
I am using method to get data
我正在使用方法来获取数据
function date() {
let str = '';
const currentTime = new Date();
const year = currentTime.getFullYear();
const month = currentTime.getMonth();
const day = currentTime.getDate();
const hours = currentTime.getHours();
let minutes = currentTime.getMinutes();
let seconds = currentTime.getSeconds();
if (month < 10) {
//month = '0' + month;
}
if (minutes < 10) {
//minutes = '0' + minutes;
}
if (seconds < 10) {
//seconds = '0' + seconds;
}
str += year + '-' + month + '-' + day + ' ' + hours + ':' + minutes + ':' + seconds + ' ';
console.log(str);
}
And as output I get
作为输出我得到
2017-6-13 20:36:6
I would like to get the same thing, but like
我想得到同样的东西，但喜欢
2017-06-13 20:36:06
But if I try one of the lines, that I commented out, for example this one
但是如果我尝试其中一行，我注释掉了，例如这一行
month = '0' + month;
I get error
我得到错误
Argument of type 'string' is not assignable to parameter of type 'number'.
How could I concat string and number?
我怎么能连接字符串和数字？
回答by Tyler Miller
Template literals(ES6+)
模板字面量(ES6+)
Instead of concatenation like month = '0' + month;You can use a template literal
而不是像 month = '0' + month;你可以使用模板文字的连接
const paddedMonth: string = `0${month}`;
Your string concatenation then turns into this for example:
您的字符串连接然后变成这样，例如：
str = `${year}-${paddedMonth}-${day} ${hours}:${minutes}:${seconds} `;
Much more readable, IMO.
更具可读性，IMO。
Union Types
联合类型
You can also use a union typewhen declaring variables.
您还可以在声明变量时使用联合类型。
let month: string | number = currentTime.getMonth();
if (month < 10) {
month = '0' + month;
}
回答by Ali Ebrahimi
if you want to work with date, you can use momentjs module: https://momentjs.com
如果你想使用日期，你可以使用 momentjs 模块：https://momentjs.com
moment().format('MMMM Do YYYY, h:mm:ss a'); // July 13th 2017, 11:18:05 pm
moment().format('dddd'); // Thursday
moment().format("MMM Do YY"); // Jul 13th 17
moment().format('YYYY [escaped] YYYY'); // 2017 escaped 2017
moment().format(); // 2017-07-13T23:18:05+04:30
and about the error you got,you most use like this:
关于你得到的错误，你最常用的是这样的：
let monthStr: string = month;
if ( month < 10) {
monthStr = '0' + month;
}
回答by abagshaw
First of all, I'm not sure why you are defining monthas a constand then trying to change it. Declare all your variables with letand convert them all to strings and you should be good to go.
首先，我不确定你为什么定义month为 aconst然后试图改变它。声明所有变量let并将它们全部转换为字符串，你应该很高兴。
function date() {
let str = '';
const currentTime = new Date();
let year = currentTime.getFullYear().toString();
let month = currentTime.getMonth().toString();
let day = currentTime.getDate().toString();
let hours = currentTime.getHours().toString();
let minutes = currentTime.getMinutes().toString();
let seconds = currentTime.getSeconds().toString();
if (month < 10) {
month = '0' + month;
}
if (minutes < 10) {
minutes = '0' + minutes;
}
if (seconds < 10) {
seconds = '0' + seconds;
}
str += year + '-' + month + '-' + day + ' ' + hours + ':' + minutes + ':' + seconds + ' ';
console.log(str);
}
See it working here: https://jsfiddle.net/40jbg8qt/
看到它在这里工作：https: //jsfiddle.net/40jbg8qt/
回答by martosfre
You could use something like this:
你可以使用这样的东西：
let pais:string = 'Ecuador';
let codigo:number = 593;
let opcionUno:string = this.pais + this.number
let opcionDos:string = this.pais.concat(this.number);
回答by libertyernie
You could also do something like this:
你也可以做这样的事情：
let month: string | number = currentTime.getMonth();
if (month < 10) month = '0' + month;
Or this:
或这个：
const month = currentTime.getMonth();
const monthStr = (month < 10 ? "0" : "") + month;
