将子字符串与字符串匹配 [英] match substring with a string

问题描述

我遇到了将子字符串与String匹配的问题。我的子串和字符串类似于

I am facing a problem in matching a substring with a String. My substring and string are something like

var str="My name is foo.I have bag(s)"
 var substr="I have bag(s)"

现在当我使用 str时。匹配（substr）它返回null可能是因为match（）函数将输入作为正则表达式而在我的情况下它与'（'。'我尝试使用'\'在圆括号之前但它没有工作。 indexOf（）函数正在运行但我不允许使用它。我也使用了test（）和exec（）但没有成功

now when I use str.match(substr) it returns null probably because match() function takes input as a regex and in my case it gets confused with the '('. I tried using '\'before round brackets but it didn't worked. indexOf() function is working but I am not allowed to use that. I also used test() and exec() but without any success

推荐答案

在现代引擎中，您只需使用 String.prototype.includes ：

In modern engines you can just use String.prototype.includes:

str.includes( substr )

如果你想要一些适用于旧浏览器的东西并避免 String.prototype.indexOf ，您可以通过手动循环实现 includes 通过字符串：

If you want something that works in older browsers and avoids String.prototype.indexOf, you could implement includes, by manually loop through the string:

String.prototype.includes = function ( substr, start ) {
    var i = typeof start === 'number' ? start : 0;
    // Condition exists early if there are not enough characters
    // left in substr for j to ever reach substr.length
    for ( var j = 0; i + substr.length < this.length + j + 1; ++i ) {
        j = substr[j] === this[i] ? j + 1 : 0;
        if ( j === substr.length )
            return true;
    }
    return false;
};

如果您坚持使用正则表达式测试，可以使用这个答案，正确地使用正则表达式中使用的substr;在这种情况下，它在（和）之前添加反斜杠：

If you are insistent on using a regex test you can use the escape function from this answer, to properly espace the substr to be used in a regex; in this case it adds a backslash before the ( and ):

new RegExp( substr.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&') ).test( str )

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