javascript split not working in IE9 - lower

问题:

I'm using IE 11 to emulate older versions of IE. The following code does not work as expected in IE 9 and below:

var search_input_val = $.trim($("#search_input").val()).replace(/\s{2,}/g, ' ');
console.log(search_input_val);
var recBox_val_arr = search_input_val.split(/\s+/); // HERE
console.log(recBox_val_arr);

recBox_val_arr is logged to the console as undefined.

The above code returns an Array on IE 10 and 11, Firefox, Chrome, Opera and Safari. Why is it not working in IE 9 and below?

More details

Given this situation:

$("#search_input").val() === "ab abc";
search_input_val === "ab abc";

recBox_val_arr is logged as undefined by IE ≤ 9, [object Array] by Firefox and ["ab", "abc"] by other browsers.

I'm linking to jQuery 1.10.2 via Google's CDN:

//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js

I also tried recBox_val_arr = search_input_val.split(' '), but recBox_val_arr is still logged as undefined.

回答1:

IE 11's implementation of IE 9's console.log is busted

There are indeed bugs with older IE's implementation of split, but that's not the problem here. In fact, split is working just fine—the real issue is IE 11's busted implementation of console.log when emulating IE 9:

console.log("test test".split(/\s+/)) // logs "undefined"
"test test".split(/\s+/)              // logs "[object Array]"

Like really, really busted

More generally, console.log in IE 11 emulating IE 9 doesn't support logging of objects or arrays:

console.log("foo");         // logs "foo"
console.log({ foo: "bar" }) // logs "undefined"
console.log(["foo"])        // logs "undefined"

Even IE 9 wasn't this bad

Worst of all, this isn't even comparable with how IE 9 actually behaves. Here's what you get if you run IE 9 directly on a VM:

console.log("test test".split(/\s+/)) // logs "test,test"

Summary

• IE 11's emulation of IE 9 isn't perfect.
• console.log is totally borked when called on IE 11 emulating IE 9.
• Always use a VM (freely available to download) for reliable cross-browser testing.

回答2:

$(document).ready(function(){
$("button").click(function(){
var search_input_val = $.trim($("#search_input").val()).replace(/\s{2,}/g, ' ');
console.log(search_input_val);
var recBox_val_arr = search_input_val.split(/\s+/); //--Here--
console.log(recBox_val_arr);
console.log(recBox_val_arr[0]);
console.log(recBox_val_arr[1]);
console.log(recBox_val_arr[2]);
});
});
Create body with
< body>
< input type="text" id="search_input" />
< button>Submit < /button>
< /body>

console.log(recBox_val_arr);

Input => hello 123 hi
Output => ["hello", "123", "hi"]

Split function in PHP is used to break string into an array.

console.log(recBox_val_arr[0]); == hello
console.log(recBox_val_arr[1]); == 123
console.log(recBox_val_arr[2]); == hi

If you put console.log() outside $("button").click(function(){}); then the value will be initially shown as "undefined".
Because it was not able to get value from text box.