匹配javascript中的特定字符

Question

我有一个字符串，我想检查它是否只包含允许的字符。

允许只有字母a，b，c，d，e，k。我想到了这样的事情：

var string1 = "abcdekabc"
if (string1 contains only a,b,c,d,e,k) {
  document.write("everything is fine");
} else { 
  document.write("there is one or more character that is not allowed");
}

我该怎么做？是否有正则表达式可以帮助我？不幸的是，我没有正则表达式的经验。

Answer 1

是的，有正则表达式：

var pattern = new RegExp('[^abcdek]', 'i');
var string1 = "abcdekabc";
if(!pattern.test(string1)){
    document.write("everything is fine");
} else { 
    document.write("there is one or more character that is not allowed");
}

可以减少到：

var string1 = "abcdekabc";
if(!(/[^abcdek]/i).test(string1)){
    document.write("everything is fine");
} else { 
    document.write("there is one or more character that is not allowed");
}

如果您愿意，可以反过来（不检查非法字符）：

var string1 = "abcdekabc";
if((/^[abcdek]+$/i).test(string1)){
    document.write("everything is fine");
} else { 
    document.write("there is one or more character that is not allowed");
}