javascript - 从字符串中提取（“获取”）一个数字(Extract (“get”) a number from a string)

Question

I have a string in javascript like `#box2' and I just want the '2' from it.

(我在javascript中有一个字符串，如`＃box2'，我只想要它的'2'。)

Tried:

(尝试：)

var thestring = $(this).attr('href');
var thenum = thestring.replace( /(^.+)(wd+w)(.+$)/i,'$2');
alert(thenum);

It still returns #box2 in the alert, how can I get it to work?

(它仍会在警报中返回＃box2，我该如何让它工作？)

It needs to accommodate for any length number attached on the end.

(它需要适应末端附加的任何长度编号。)

  ask by user1022585 translate from so

Answer 1

For this specific example,

(对于这个具体的例子，)

 var thenum = thestring.replace( /^D+/g, ''); // replace all leading non-digits with nothing

in the general case:

(在一般情况下：)

 thenum = "foo3bar5".match(/d+/)[0] // "3"

Since this answer gained popularity for some reason, here's a bonus: regex generator.

(由于这个答案因某种原因而受到欢迎，这里有一个奖励：正则表达式生成器。)

 function getre(str, num) { if(str === num) return 'nice try'; var res = [/^\D+/g,/\D+$/g,/^\D+|\D+$/g,/\D+/g,/\D.*/g, /.*\D/g,/^\D+|\D.*$/g,/.*\D(?=\d)|\D+$/g]; for(var i = 0; i < res.length; i++) if(str.replace(res[i], '') === num) return 'num = str.replace(/' + res[i].source + '/g, "")'; return 'no idea'; }; function update() { $ = function(x) { return document.getElementById(x) }; var re = getre($('str').value, $('num').value); $('re').innerHTML = 'Numex speaks: <code>' + re + '</code>'; } 

 <p>Hi, I'm Numex, the Number Extractor Oracle. <p>What is your string? <input id="str" value="42abc"></p> <p>What number do you want to extract? <input id="num" value="42"></p> <p><button onclick="update()">Insert Coin</button></p> <p id="re"></p>