IE8 is not recognizing my regular expression

I'm trying to parse an AJAX response and get the id of the body tag. I can't do this via jQuery, though, because jQuery can't emulate a DOM response for a body tag.

I've split this into many lines to try and isolate the error. This works in modern browsers, but it's failing in IE8.

var bodyIDregex = new RegExp(/<body[^>]*id=["'](.*?)["']>/gi),
matched = html.match(bodyIDregex),
bodyID = bodyIDregex.exec(matched[0]);
bodyID = bodyID[1];

I have confirmed that the value of the variable html is as expected.

Any help?

Thanks!

标签： javascript regex internet-explorer-8

2条回答

老娘就宠你

2楼-- · 2019-01-29 04:37

You should either pass a string to the constructor for regexen, or use the regex literal syntax, but not both.

var bodyIDregex = /<body[^>]*id=["'](.*?)["']>/gi

var bodyIDregex = new RegExp("<body[^>]*id=[\"'](.*?)[\"']>","gi")

Update:

As you have correctly identified in your answer, the problem stems from the fact that the regex search continues from the position of the last character in the previous match. One way to correct this is to reset lastIndex, but in this case this is not required, since you only need to match against the string once:

var bodyIDregex = /<body[^>]*id=["'](.*?)["']>/gi,
    bodyID = bodyIDregex.exec(html);

//bodyID is now the array, ["<body id="test">asdf</body>", "test"]

alert(bodyID[1]);
//alerts the captured group, "test"

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劳资没心，怎么记你

3楼-- · 2019-01-29 04:55

Apparently, when you call (RegExp object).match(string), it increments a property of the RegExp object called lastIndex. I am not completely familiar with how the RegExp object works, but this causes an issue when trying to call the exec() method later.

The solution, apparently, is to reset lastIndex to zero.

var html = '<html><body id="test">asdf</body></html>';

var bodyIDregex = /<body[^>]*id=["'](.*?)["']>/gi,
matched = html.match(bodyIDregex);
// Reset lastIndex
bodyIDregex.lastIndex = 0;
var bodyID = bodyIDregex.exec(matched[0]);
alert(bodyID.length);
bodyID = bodyID[1];

document.write(bodyID); // writes test

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IE8 is not recognizing my regular expression

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