如何在Javascript中将字符串修剪为N个字符？

Question

我怎么能使用Javascript创建一个函数来修剪作为参数传递的字符串到指定的长度,也作为参数传递.例如:

var string = "this is a string";
var length = 6;
var trimmedString = trimFunction(length, string);

// trimmedString should be:
// "this is"

有人有想法吗？我听说过使用子字符串,但不太明白.

Answer 1

为什么不使用substring ... string.substring(0, 7);第一个参数(0)是起点.第二个参数(7)是结束点(不包括).更多信息在这里.

var string = "this is a string";
var length = 7;
var trimmedString = string.substring(0, length);

Answer 2

将Will的评论复制到答案中,因为我发现它很有用:

var string = "this is a string";
var length = 20;
var trimmedString = string.length > length ? 
                    string.substring(0, length - 3) + "..." : 
                    string;

谢谢威尔.

对于任何关心https://jsfiddle.net/t354gw7e/ :)的人来说都是一个小问题

Answer 3

我建议使用扩展代码整洁.请注意,扩展内部对象原型可能会使依赖它们的库变得混乱.

String.prototype.trimEllip = function (length) {
  return this.length > length ? this.substring(0, length) + "..." : this;
}

并使用它像:

var stringObject= 'this is a verrrryyyyyyyyyyyyyyyyyyyyyyyyyyyyylllooooooooooooonggggggggggggsssssssssssssttttttttttrrrrrrrrriiiiiiiiiiinnnnnnnnnnnnggggggggg';
stringObject.trimEllip(25)

Answer 4

优于String.prototype.slice方法String.prototype.substring（在substring中，在某些情况下它给出的结果与您期望的不同）。

从左到右修剪字符串：

const str = "123456789";
result = str.slice(0,5);     // "12345", extracts first 5 characters
result = str.substring(0,5); // "12345"

开始索引 > 结束索引：

result = str.slice(5,0);     // "", empty string
result = str.substring(5,0); // "12345" , swaps start & end indexes => str.substring(0,5)

从右向左修剪字符串： (-ve start index)

result = str.slice(-3);                 // "789", extracts last 3 characters
result = str.substring(-3);             // "123456789" , -ve becomes 0 => str.substring(0)
result = str.substring(str.length - 3); // "789"

Answer 5

https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/String/substr

来自链接:

string.substr(start[, length])

Answer 6

    let trimString = function (string, length) {
      return string.length > length ? 
             string.substring(0, length) + '...' :
             string;
    };

使用案例，

let string = 'How to trim a string to N chars in Javascript';

trimString(string, 20);

//How to trim a string...