Javascript-有更好的方法来检查字符串而不是indexOf

Question

我使用此代码，我的问题是，是否有比indexOf更好的方法来检查字符串：

if(documentFile.ending.indexOf('pdf') > -1 || documentFile.ending.indexOf('PDF') > -1 || documentFile.ending.indexOf('docx') > -1)

Answer 1

ES6 has boolean function. Use:

if ( documentFile.ending.includes('pdf') ) { }

Or for regex:

if ( documentFile.ending.match(/your-regex/) { }

Example spec: https://developer.mozilla.org/nl/docs/Web/JavaScript/Reference/Global_Objects/String/includes

Answer 2

If you are using ES6 then you may want to look at String.prototype.includes

var str = 'To be, or not to be, that is the question.';
console.log(str.includes('To be'));       // true

Answer 3

In ES6 you have better option to use "includes"

otherwise use regex

if(/pdf/i.test(documentFile.ending)) 

Answer 4

Well, indexOf is really fast, a lot faster than using a regular expression. But something like /pdf$/i.test(str) lets you test the end as well as giving you case-insensitivity. But you could be more precise:

function endsWith(str, ending) {
    return str != null
        && ending != null
        && ending.length <= str.length
        && str.lastIndexOf(ending) === str.length - ending.length;
}

Note the ending.length <= str.length which is there so that you don't do something like endsWith("", "a") and get true . :)