下面的函数获取第一个匹配项

function getStringBetween(x: string, start: string, end: string) {
  const regex = new RegExp(`${start}(.*?)${end}`)

  if (regex.test(x)) {
    return regex.exec(x)![1]
  } else return undefined
}

有测试

test("getStringBetween", () => {
  const result = getStringBetween("<em> Jai Ram</em>", "<em>", "</em>")
  expect(result).toEqual(" Jai Ram")
  const result1 = getStringBetween(
    "hare Jai Ram hare hare hare",
    "hare",
    "hare"
  )
  expect(result1).toEqual(" Jai Ram ")
})

你可以试试这个

var mySubString = str.substring(
    str.indexOf(":") + 1, 
    str.lastIndexOf(";")
);

你也可以用这个…

function extractText(str,delimiter){ if (str && delimiter){ var firstIndex = str.indexOf(delimiter)+1; var lastIndex = str.lastIndexOf(delimiter); str = str.substring(firstIndex,lastIndex); } return str; } var quotes = document.getElementById("quotes"); // &#34 - represents quotation mark in HTML <div> <div> <span id="at"> My string is @between@ the "at" sign </span> <button onclick="document.getElementById('at').innerText = extractText(document.getElementById('at').innerText,'@')">Click</button> </div> <div> <span id="quotes"> My string is "between" quotes chars </span> <button onclick="document.getElementById('quotes').innerText = extractText(document.getElementById('quotes').innerText,'&#34')">Click</button> </div> </div>

我喜欢这个方法:

var str = 'MyLongString:StringIWant;';
var tmpStr  = str.match(":(.*);");
var newStr = tmpStr[1];
//newStr now contains 'StringIWant'

var str = '[basic_salary]+100/[basic_salary]';
var arr = str.split('');
var myArr = [];
for(var i=0;i<arr.length;i++){
    if(arr[i] == '['){
        var a = '';
        for(var j=i+1;j<arr.length;j++){
            if(arr[j] == ']'){
                var i = j-1;
                break;
            }else{
                a += arr[j];
            }
        }
        myArr.push(a);
    }
    var operatorsArr = ['+','-','*','/','%'];
    if(operatorsArr.includes(arr[i])){
        myArr.push(arr[i]);
    }
    var numbArr = ['0','1','2','3','4','5','6','7','8','9'];
    if(numbArr.includes(arr[i])){
        var a = '';
        for(var j=i;j<arr.length;j++){
            if(numbArr.includes(arr[j])){
                a += arr[j];
            }else{
                var i = j-1;
                break;
            }
        }
        myArr.push(a);
    }
}
myArr = ["basic_salary", "+", "100", "/", "basic_salary"]

@Babasaheb Gosavi回答是完美的，如果你有一个子字符串出现(“:”和“;”)。但一旦出现多次，就有点棘手了。

我在多个项目中提出的最佳解决方案是在一个对象中使用四个方法。

第一种方法:实际上是从两个字符串之间获得一个子字符串(但是它只会找到一个结果)。 第二种方法:删除(可能的)最近发现的结果及其前后的子字符串。 第三种方法:将上述两种方法递归地处理一个字符串。 第四种方法:将应用第三种方法并返回结果。

Code

说得够多了，让我们看看代码:

var getFromBetween = {
    results:[],
    string:"",
    getFromBetween:function (sub1,sub2) {
        if(this.string.indexOf(sub1) < 0 || this.string.indexOf(sub2) < 0) return false;
        var SP = this.string.indexOf(sub1)+sub1.length;
        var string1 = this.string.substr(0,SP);
        var string2 = this.string.substr(SP);
        var TP = string1.length + string2.indexOf(sub2);
        return this.string.substring(SP,TP);
    },
    removeFromBetween:function (sub1,sub2) {
        if(this.string.indexOf(sub1) < 0 || this.string.indexOf(sub2) < 0) return false;
        var removal = sub1+this.getFromBetween(sub1,sub2)+sub2;
        this.string = this.string.replace(removal,"");
    },
    getAllResults:function (sub1,sub2) {
        // first check to see if we do have both substrings
        if(this.string.indexOf(sub1) < 0 || this.string.indexOf(sub2) < 0) return;

        // find one result
        var result = this.getFromBetween(sub1,sub2);
        // push it to the results array
        this.results.push(result);
        // remove the most recently found one from the string
        this.removeFromBetween(sub1,sub2);

        // if there's more substrings
        if(this.string.indexOf(sub1) > -1 && this.string.indexOf(sub2) > -1) {
            this.getAllResults(sub1,sub2);
        }
        else return;
    },
    get:function (string,sub1,sub2) {
        this.results = [];
        this.string = string;
        this.getAllResults(sub1,sub2);
        return this.results;
    }
};

如何使用?

例子:

var str = 'this is the haystack {{{0}}} {{{1}}} {{{2}}} {{{3}}} {{{4}}} some text {{{5}}} end of haystack';
var result = getFromBetween.get(str,"{{{","}}}");
console.log(result);
// returns: [0,1,2,3,4,5]