如何在Typescript中小写字符串？

Question

I am comparing two strings and I want to lower case a string before comparing. How can I do this? This is my code:

 this.products = response.responseData.sort(function(a,b){

                     if(a.product.productName < b.product.productName){
                         return -1;
                     }
                     if(a.product.productName > b.product.productName){
                         return 1;
                     }
                     return 0;
                 });

Answer 1

Just use the:

.toLowerCase()

method.

In your case:

 if(a.product.productName.toLowerCase() < b.product.productName.toLowerCase()){ return -1; }

Answer 2

Use Javascript's .toLowerCase().

this.products = response.responseData.sort(function(a,b){

                 if(a.product.productName.toLowerCase() < b.product.productName.toLowerCase()){
                     return -1;
                 }
                 if(a.product.productName.toLowerCase() > b.product.productName.toLowerCase()){
                     return 1;
                 }
                 return 0;
             });

Answer 3

如果您在angular 2中使用jQuery，请使用toString函数

$('#search').val().toString().toLowerCase()

Answer 4

You can use new string case operators which are available in TypeScript 4.1.0

Please see example:

type LowerCase<T extends string> = `${lowercase T}`;
const lower = <T extends string>(str: T) => str.toLowerCase() as LowerCase<T>;
const result = lower('UP'); // 'up'

For more information see this PR