Javascript：使用 OR 操作数将单个值与多个值进行比较
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Javascript: Comparing SINGLE Value Against MULTIPLE Values with OR Operands
提问by AlecPerkey
Possible Duplicate:
Check variable equality against a list of values
Javascript if statement with multiple permissible conditions
I must click the same 21 of 253 items (li) in a dropdown list (ul).
我必须在下拉列表 (ul) 中单击 253 个项目中的 21 个 (li)。
Scrolling I'll have to do this for the same list on 500+ pages, I figured I could Javascript inject each ul, loop through and click each li which happens to be one of the 21. It seems I cannot do something like
滚动 我必须为 500 多个页面上的同一个列表执行此操作，我想我可以通过 Javascript 注入每个 ul，循环并单击每个 li，它恰好是 21 个中的一个。看来我不能做类似的事情
if(item[i] === ('aasdf'|'basdf'|'cwefw'|'asdfd'|'trehe'|'ferth'|'erthg'|'erthh'|'ierth'|'jeth'|'kerth'|'lerth'|'merth'|'psdfg'|'gregq'|'rsrgs'|'sress'|'srget'|'sergu'|'sdfgsv'))
Is there a syntactically cleaner way of writing this ugly if statement below?
是否有一种语法更清晰的方式来编写下面这个丑陋的 if 语句？
var item = document.getElementById('myDropdownList').getElementsByTagName('li');
for (i=0;i<item.length;i++){
if(item[i].innerText === 'Argentina' | item[i].innerText === 'Australia' | item[i].innerText === 'Brazil' | item[i].innerText === 'Canada' | item[i].innerText === 'China' | item[i].innerText === 'Colombia' | item[i].innerText === 'France' | item[i].innerText === 'Germany' | item[i].innerText === 'Indonesia' | item[i].innerText === 'India' | item[i].innerText === 'Italy' | item[i].innerText === 'Japan' | item[i].innerText === 'Malaysia' | item[i].innerText === 'Mexico' | item[i].innerText === 'Philippines' | item[i].innerText === 'Russia' | item[i].innerText === 'South Africa' | item[i].innerText === 'Sweden' | item[i].innerText === 'Switzerland' | item[i].innerText === 'United Kingdom' | item[i].innerText === 'USA'){
item[i].click();
}
}
回答by Bergi
You could use a variable and multiple comparison, but that's still lengthy:
您可以使用变量和多重比较，但这仍然很长：
var text = item[i].innerText;
if (text === 'Argentina' | text === 'Australia' | text === 'Brazil' | text === 'Canada' | text === 'China' | text === 'Colombia' | text === 'France' | text === 'Germany' | text === 'Indonesia' | text === 'India' | text === 'Italy' | text === 'Japan' | text === 'Malaysia' | text === 'Mexico' | text === 'Philippines' | text === 'Russia' | text === 'South Africa' | text === 'Sweden' | text === 'Switzerland' | text === 'United Kingdom' | text === 'USA')
Or you could just use an array and check if the string is contained in it.
或者您可以只使用一个数组并检查字符串是否包含在其中。
var matches = ['Argentina','Australia','Brazil','Canada','China','Colombia','France','Germany','Indonesia','India','Italy','Japan','Malaysia','Mexico','Philippines','Russia','South Africa','Sweden','Switzerland','United Kingdom','USA'];
if (~ matches.indexOf(item[i].innerText) …
Yet, for the complicated != -1comparisonand the lack of native indexOfin older IEs, people tend to use regexes:
然而，对于复杂的!= -1比较和indexOf旧 IE 中缺乏本机，人们倾向于使用正则表达式：
var regex = /Argentina|Australia|Brazil|Canada|China|Colombia|France|Germany|Indonesia|India|Italy|Japan|Malaysia|Mexico|Philippines|Russia|South Africa|Sweden|Switzerland|United Kingdom|USA/
if (regex.test(item[i].innerText)) …
回答by Brad Christie
var options = ['Argentina', 'Australia', 'Brazil', 'Canada', ...];
if (options.indexOf(item[i].innerText) !== -1){
// item[i] was found in options
}
Something like that? use Array.indexOf(Unless I've mis-read the question? In which case post a comment and I'll do my best to re-work my answer)
类似的东西？使用Array.indexOf（除非我误读了问题？在这种情况下发表评论，我会尽力重新回答我的答案）
