问题:

Is this code safe in all major browsers?

var string = '123'
alert(string[1] == '2') // should alert true

回答1:

No, it's not safe. Internet Explorer 7 doesn't support accessing strings by index.

You have to use the charAt method to be compatibale with IE7:

var string = '123';
alert(string.charAt(1) == '2');

回答2:

Everything in JavaScript is an object; arrays, functions, strings, everything. The piece of code you put up is perfectly valid, although a little confusing - there are much better ways of doing that

var str = '123';
str[1] === '2'; // true, as you've just discovered (if you're not in IE7)
// Better ways:
str.indexOf('2'); // 1
str.charAt(1); // '2'
str.substr(1, 1); // '2'
str.split(''); // ['1', '2', '3']

The better ways make sure anyone else reading your code (either someone else or yourself in 6 months time) don't thing that str is an array. It makes your code a lot easier to read and maintain

回答3:

I tested in IE7, IE8, Safari, Chrome, and FF. All worked just fine!

EDIT just for kicks it works in Konqueror also! Js Fiddle example

回答4:

I don't really see why you can't do that...though alternatively, you can use .substring()

回答5:

It will work. It might be a problem if you decide to use browser specific functions (I.E xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); only works in internet explorer)