你可以让所有东西都小写:

var string="Stackoverflow is the BEST";
var searchstring="best";
var result= (string.toLowerCase()).search((searchstring.toLowerCase()));
alert(result);

你可以让所有东西都小写:

var string="Stackoverflow is the BEST";
var searchstring="best";
var result= (string.toLowerCase()).search((searchstring.toLowerCase()));
alert(result);

ES6 +:

let string="Stackoverflow is the BEST";
let searchstring="best";


let found = string.toLowerCase()
                  .includes(searchstring.toLowerCase());

includes()如果searchString出现在一个或多个位置则返回true，否则返回false。

我在尝试区分大小写的字符串搜索，我尝试了

 var result = string.toLowerCase().match(searchstring) 

也

var result= string.search(new RegExp(searchstring, "i"));

但我做了一些小修改，对我有用

var result = string.match(new RegExp(searchstring, "i"));

这也可以是小写，大写或组合

是的，使用。match，而不是。search。match调用的结果将返回匹配的实际字符串本身，但它仍然可以用作布尔值。

var string = "Stackoverflow is the BEST";
var result = string.match(/best/i);
// result == 'BEST';

if (result){
    alert('Matched');
}

使用这样的正则表达式可能是JavaScript中最整洁、最明显的方法，但请记住，它是正则表达式，因此可能包含正则元字符。如果你想从其他地方获取字符串(例如，用户输入)，或者如果你想避免转义大量元字符，那么你可能最好像这样使用indexOf:

matchString = 'best';
// If the match string is coming from user input you could do
// matchString = userInput.toLowerCase() here.

if (string.toLowerCase().indexOf(matchString) != -1){
    alert('Matched');
}

假设我们想要在字符串变量大海捞针。这里有三个陷阱:

Internationalized applications should avoid string.toUpperCase and string.toLowerCase. Use a regular expression which ignores case instead. For example, var needleRegExp = new RegExp(needle, "i"); followed by needleRegExp.test(haystack). In general, you might not know the value of needle. Be careful that needle does not contain any regular expression special characters. Escape these using needle.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&");. In other cases, if you want to precisely match needle and haystack, just ignoring case, make sure to add "^" at the start and "$" at the end of your regular expression constructor.

考虑到第(1)和(2)点，一个例子是:

var haystack = "A. BAIL. Of. Hay.";
var needle = "bail.";
var needleRegExp = new RegExp(needle.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&"), "i");
var result = needleRegExp.test(haystack);
alert(result);