Question

我有一个字符串跟随Jack_XX3_20，我需要根据XX3的位置检索20。我使用以下代码，但它返回k_XX3

<!DOCTYPE html>
<html>
<body>

<p>Test The Code</p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

<script>
function myFunction() {
    var str = "Jack_XX3_20YYYG";
    var pos = str.indexOf("XX3");
    var n = str.substring(pos+3,3);
    document.getElementById("demo").innerHTML = n;
}
</script>

</body>
</html>
</script>

Answer 1

这样的东西？

str.substring(str.indexOf("XX3")+4, str.length)

这就是你想要使用子串的方法

str.substring（indexA [，indexB]）

<强>索引A

An integer between 0 and the length of the string, specifying the offset into the string of the first character to include in the returned substring.

<强> indexB

Optional. An integer between 0 and the length of the string, which specifies the offset into the string of the first character not to include in the returned substring.

来源：mdn

<强>更新

您正在根据评论

寻找正则表达式

＆＃13;

var str = "Jack_XX3_24930YYYG";
var reg = /XX3_(\+?\d+)/g;
var match = reg.exec(str);
alert(match[1]);

＆＃13;

Answer 2

这应该有效（在JSFiddle中测试）：

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

<script>
function myFunction() {
    var str = "Jack_XX3_20";
    var pos = str.indexOf("XX3_")+4;
    var n = str.substring(pos,str.length);
    document.getElementById("demo").innerHTML = n;
}
</script>

</body>

Answer 3

试试这个

function myFunction() {
   var str = "Jack_XX3_20qjjjj";
    var pos = str.lastIndexOf("XX3_")+3;

    var pos = str.indexOf("XX3_")+4;
    var n = str.substring(pos,pos+2);
    document.getElementById("demo").innerHTML = n;
}

<强> DEMO

如何根据JavaScript中字符的位置提取子字符串？

3 个答案: