Javascript未定义错误：ReferenceError：未定义ALT

Question

它应该做什么 - 实施例

url1(pages,"ALT") returns "www.xyz.ac.uk" 
url1(pages,"xyz") returns ""

错误 - ReferenceError: ALT is not defined

这只是为了一些课程，我坚持这些错误。任何帮助将不胜感激

function index(string,pattern,caseSensitive) {
    if(caseSensitive == false) {
        var v = string.toUpperCase();
    } else {
        var v = string;
    }

    return indexNumber = v.indexOf(pattern);
}
var pages = [ "|www.lboro.ac.uk|Loughborough University offers degree programmes and world class research.", "!www.xyz.ac.uk!An alternative University" , "%www%Yet another University"];

    alert(url1(pages, ALT));

function url1(pages,pattern) {
    var siteContent = [];
    for(i=0;i<pages.length;i++) {
        var seperator = pages[i].charAt(0);
        if(pages[i].indexOf(seperator)>0){
            siteContent = pages[i].split(pages[i].indexOf(seperator));      
        }
        if( index(siteContent[2],pattern,false)>=0){
            return siteContent[1]; 
        }else{
            return "";
        }

    }
}

Answer 1

所以你这样称呼它：

alert(url1(pages, ALT));

此处alt未定义，因为ALT不是已定义的变量。

用字符串调用它？

url1(pages,"ALT");