[英]How to trim a string to N chars in Javascript?
How can I, using Javascript, make a function that will trim string passed as argument, to a specified length, also passed as argument.我如何使用 Javascript 制作一个 function 来修剪作为参数传递的字符串,使其达到指定的长度,也作为参数传递。 For example:例如:
var string = "this is a string";
var length = 6;
var trimmedString = trimFunction(length, string);
// trimmedString should be:
// "this is"
Anyone got ideas?有人有想法吗? I've heard something about using substring, but didn't quite understand.我听说过一些关于使用 substring 的事情,但不是很明白。
Why not just use substring... string.substring(0, 7);
为什么不直接使用子字符串... string.substring(0, 7);
The first argument (0) is the starting point.第一个参数 (0) 是起点。 The second argument (7) is the ending point (exclusive).第二个参数 (7) 是终点(不包括)。 More info here. 更多信息在这里。
var string = "this is a string";
var length = 7;
var trimmedString = string.substring(0, length);
Copying Will's comment into an answer, because I found it useful: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;
Thanks Will.谢谢威尔。
And a jsfiddle for anyone who cares https://jsfiddle.net/t354gw7e/ :)对于任何关心https://jsfiddle.net/t354gw7e/ 的人来说,这是一个 jsfiddle :)
I suggest to use an extension for code neatness.我建议使用扩展来保持代码整洁。 Note that extending an internal object prototype could potentially mess with libraries that depend on them.请注意,扩展内部对象原型可能会干扰依赖它们的库。
String.prototype.trimEllip = function (length) {
return this.length > length ? this.substring(0, length) + "..." : this;
}
And use it like:并像这样使用它:
var stringObject= 'this is a verrrryyyyyyyyyyyyyyyyyyyyyyyyyyyyylllooooooooooooonggggggggggggsssssssssssssttttttttttrrrrrrrrriiiiiiiiiiinnnnnnnnnnnnggggggggg';
stringObject.trimEllip(25)
https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/String/substr https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/String/substr
From link:来自链接:
string.substr(start[, length])
Little late... I had to respond.有点晚了......我不得不回应。 This is the simplest way.这是最简单的方法。
// JavaScript function fixedSize_JS(value, size) { return value.padEnd(size).substring(0, size); } // JavaScript (Alt) var fixedSize_JSAlt = function(value, size) { return value.padEnd(size).substring(0, size); } // Prototype (preferred) String.prototype.fixedSize = function(size) { return this.padEnd(size).substring(0, size); } // Overloaded Prototype function fixedSize(value, size) { return value.fixedSize(size); } // usage console.log('Old school JS -> "' + fixedSize_JS('test (30 characters)', 30) + '"'); console.log('Semi-Old school JS -> "' + fixedSize_JSAlt('test (10 characters)', 10) + '"'); console.log('Prototypes (Preferred) -> "' + 'test (25 characters)'.fixedSize(25) + '"'); console.log('Overloaded Prototype (Legacy support) -> "' + fixedSize('test (15 characters)', 15) + '"');
Step by step.一步步。 .padEnd - Guarentees the length of the string .padEnd - 保证字符串的长度
"The padEnd() method pads the current string with a given string (repeated, if needed) so that the resulting string reaches a given length. The padding is applied from the end (right) of the current string. The source for this interactive example is stored in a GitHub repository." “padEnd() 方法用给定的字符串填充当前字符串(重复,如果需要),以便结果字符串达到给定的长度。填充是从当前字符串的末尾(右侧)应用的。此交互式的源示例存储在 GitHub 存储库中。” source: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…来源:developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/...
.substring - limits to the length you need .substring - 限制你需要的长度
If you choose to add ellipses, append them to the output.如果您选择添加省略号,请将它们附加到输出中。
I gave 4 examples of common JavaScript usages.我给出了 4 个常见的 JavaScript 用法示例。 I highly recommend using the String prototype with Overloading for legacy support.我强烈建议使用带有重载的 String 原型来获得遗留支持。 It makes it much easier to implement and change later.它使以后实施和更改变得更加容易。
let trimString = function (string, length) {
return string.length > length ?
string.substring(0, length) + '...' :
string;
};
Use Case,用例,
let string = 'How to trim a string to N chars in Javascript';
trimString(string, 20);
//How to trim a string...
Just another suggestion, removing any trailing white-space只是另一个建议,删除任何尾随空格
limitStrLength = (text, max_length) => {
if(text.length > max_length - 3){
return text.substring(0, max_length).trimEnd() + "..."
}
else{
return text
}
There are several ways to do achieve this有几种方法可以做到这一点
let description = "your test description your test description your test description";
let finalDesc = shortMe(description, length);
function finalDesc(str, length){
// return str.slice(0,length);
// return str.substr(0, length);
// return str.substring(0, length);
}
You can also modify this function to get in between strings as well.您还可以修改此函数以进入字符串之间。
Prefer String.prototype.slice
over the String.prototype.substring
method (in substring , for some cases it gives a different result than what you expect).更喜欢String.prototype.slice
而不是String.prototype.substring
方法(在substring中,在某些情况下,它给出的结果与您期望的不同)。
Trim the string from LEFT to RIGHT: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"
startIndex > endIndex: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)
Trim the string from RIGHT to LEFT: (-ve start index)
从 RIGHT 到 LEFT 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"
Here is my solution, which includes trimming white space too.这是我的解决方案,其中也包括修剪空白。
const trimToN = (text, maxLength, dotCount) => {
let modText = text.trim();
if (modText.length > maxLength) {
modText = text.substring(0, maxLength - dotCount);
modText = modText.padEnd(maxLength, ".");
return modText;
}
return text;
};
trimToN('Javascript', 6, 2) will return "Java.." trimToN('Javascript', 6, 2) 将返回“Java..”
I think that you should use this code :-)我认为您应该使用此代码:-)
// sample string
const param= "Hi you know anybody like pizaa";
// You can change limit parameter(up to you)
const checkTitle = (str, limit = 17) => {
var newTitle = [];
if (param.length >= limit) {
param.split(" ").reduce((acc, cur) => {
if (acc + cur.length <= limit) {
newTitle.push(cur);
}
return acc + cur.length;
}, 0);
return `${newTitle.join(" ")} ...`;
}
return param;
};
console.log(checkTitle(str));
// result : Hi you know anybody ...
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