Javascript 在特定索引处插入字符串
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原文地址: http://stackoverflow.com/questions/4313841/
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Insert a string at a specific index
提问by Jiew Meng
How can I insert a string at a specific index of another string?
如何在另一个字符串的特定索引处插入一个字符串？
var txt1 = "foo baz"
Suppose I want to insert "bar " after the "foo" how can I achieve that?
假设我想在“foo”之后插入“bar”，我该如何实现？
I thought of substring(), but there must be a simpler more straight forward way.
我想到了substring()，但必须有更简单更直接的方法。
采纳答案by user113716
You could prototype your own splice()into String.
您可以将自己的原型制作splice()为 String。
Polyfill
填充物
if (!String.prototype.splice) {
/**
* {JSDoc}
*
* The splice() method changes the content of a string by removing a range of
* characters and/or adding new characters.
*
* @this {String}
* @param {number} start Index at which to start changing the string.
* @param {number} delCount An integer indicating the number of old chars to remove.
* @param {string} newSubStr The String that is spliced in.
* @return {string} A new string with the spliced substring.
*/
String.prototype.splice = function(start, delCount, newSubStr) {
return this.slice(0, start) + newSubStr + this.slice(start + Math.abs(delCount));
};
}
Example
例子
String.prototype.splice = function(idx, rem, str) {
return this.slice(0, idx) + str + this.slice(idx + Math.abs(rem));
};
var result = "foo baz".splice(4, 0, "bar ");
document.body.innerHTML = result; // "foo bar baz"EDIT:Modified it to ensure that remis an absolute value.
编辑：修改它以确保它rem是一个绝对值。
回答by Tim Down
Inserting at a specific index (rather than, say, at the first space character) has to use string slicing/substring:
在特定索引处插入（而不是在第一个空格字符处）必须使用字符串切片/子字符串：
var txt2 = txt1.slice(0, 3) + "bar" + txt1.slice(3);
回答by Base33
Here is a method I wrote that behaves like all other programming languages:
这是我编写的一个方法，它的行为与所有其他编程语言一样：
String.prototype.insert = function(index, string) {
if (index > 0)
{
return this.substring(0, index) + string + this.substring(index, this.length);
}
return string + this;
};
//Example of use:
var something = "How you?";
something = something.insert(3, " are");
console.log(something)Reference:
参考：
回答by Base33
Just make the following function:
只需执行以下功能：
function insert(str, index, value) {
return str.substr(0, index) + value + str.substr(index);
}
and then use it like that:
然后像这样使用它：
alert(insert("foo baz", 4, "bar "));
Output: foo bar baz
输出： foo bar baz
It behaves exactly, like the C# (Sharp) String.Insert(int startIndex, string value).
它的行为与 C# (Sharp) String.Insert(int startIndex, string value) 完全一样。
NOTE:This insert function inserts the string value(third parameter) beforethe specified integer index(second parameter) in the string str(first parameter), and then returns the new string without changing str!
注意：此插入函数在字符串str（第一个参数）中指定整数索引（第二个参数）之前插入字符串值（第三个参数），然后返回新字符串而不更改str！
回答by VisioN
UPDATE 2016:Here is another just-for-fun(but more serious!) prototype function based on one-liner RegExpapproach (with prepend support on undefinedor negative index):
2016 年更新：这是另一个基于单行方法（带有 prepend 支持 on或 negative ）的有趣（但更严重！）原型函数：RegExpundefinedindex
/**
* Insert `what` to string at position `index`.
*/
String.prototype.insert = function(what, index) {
return index > 0
? this.replace(new RegExp('.{' + index + '}'), '$&' + what)
: what + this;
};
console.log( 'foo baz'.insert('bar ', 4) ); // "foo bar baz"
console.log( 'foo baz'.insert('bar ') ); // "bar foo baz"
Previous (back to 2012) just-for-funsolution:
以前（回到 2012 年）只是为了好玩的解决方案：
var index = 4,
what = 'bar ';
'foo baz'.replace(/./g, function(v, i) {
return i === index - 1 ? v + what : v;
}); // "foo bar baz"
回答by Jake Stoeffler
If anyone is looking for a way to insert text at multiple indices in a string, try this out:
如果有人正在寻找一种在字符串中的多个索引处插入文本的方法，请尝试以下操作：
String.prototype.insertTextAtIndices = function(text) {
return this.replace(/./g, function(character, index) {
return text[index] ? text[index] + character : character;
});
};
For example, you can use this to insert <span>tags at certain offsets in a string:
例如，您可以使用它<span>在字符串中的某些偏移处插入标签：
var text = {
6: "<span>",
11: "</span>"
};
"Hello world!".insertTextAtIndices(text); // returns "Hello <span>world</span>!"
回答by Ryan Ore
This is basically doing what @Bass33 is doing except I'm also giving the option of using a negative index to count from the end. Kind of like the substr method allows.
这基本上是在做@Bass33 正在做的事情，除了我还提供了使用负索引从末尾开始计数的选项。有点像 substr 方法允许的那样。
// use a negative index to insert relative to the end of the string.
String.prototype.insert = function (index, string) {
var ind = index < 0 ? this.length + index : index;
return this.substring(0, ind) + string + this.substring(ind, this.length);
};
Use case: Lets say you have full size images using a naming convention but can't update the data to also provide thumbnail urls.
用例：假设您拥有使用命名约定的全尺寸图像，但无法更新数据以提供缩略图 url。
var url = '/images/myimage.jpg';
var thumb = url.insert(-4, '_thm');
// result: '/images/myimage_thm.jpg'
回答by dxh
Given your current example you could achieve the result by either
鉴于您当前的示例，您可以通过以下任一方式获得结果
var txt2 = txt1.split(' ').join(' bar ')
or
或者
var txt2 = txt1.replace(' ', ' bar ');
but given that you can make such assumptions, you might as well skip directly to Gullen's example.
但鉴于您可以做出这样的假设，您不妨直接跳到 Gullen 的示例。
In a situation where you really can't make any assumptions other than character index-based, then I really would go for a substring solution.
在除了基于字符索引之外你真的无法做出任何假设的情况下，我真的会选择子字符串解决方案。
回答by user40521
my_string = "hello world";
my_insert = " dear";
my_insert_location = 5;
my_string = my_string.split('');
my_string.splice( my_insert_location , 0, my_insert );
my_string = my_string.join('');
回答by kamal
Well, we can use both the substring and slice method.
好吧，我们可以同时使用 substring 和 slice 方法。
String.prototype.customSplice = function (index, absIndex, string) {
return this.slice(0, index) + string+ this.slice(index + Math.abs(absIndex));
};
String.prototype.replaceString = function (index, string) {
if (index > 0)
return this.substring(0, index) + string + this.substring(index, this.length);
return string + this;
};
console.log('Hello Developers'.customSplice(6,0,'Stack ')) // Hello Stack Developers
console.log('Hello Developers'.replaceString(6,'Stack ')) //// Hello Stack Developers
The only problem of a substring method is that it won't work with a negative index. It's always take string index from 0th position.
子字符串方法的唯一问题是它不适用于负索引。它总是从第 0 个位置获取字符串索引。
