jQuery for（x在y）循环

Question

In the following code the variable " key " isn't capitalized even though any other variables, such as steve[j], are capitalized if they replace " key " in the call to the function capitaliseFirstLetter() .

Could someone tell me why?

for(key in aray) {
    steve = aray[key];
    for(j = 0; j < steve.length; j++){
        diff = steve[j].slice(key.length);
        if(diff == ""){
            diff = "_";
        }
        diffs.push(diff);
        var firstLetterUpper = /^[A-Z]/.test(steve[j]);
        if(firstLetterUpper){
            capitaliseFirstLetter(key)
            alert(key])
        }

    }
}
function capitaliseFirstLetter(string){
    return string.charAt(0).toUpperCase() + string.slice(1);
}

Answer 1

key = capitaliseFirstLetter(key)
alert(key)

string object is passed to function by value. So it's not changing you should reaasign value

Answer 2

If your aim is to captitalise each word it can be done more simply as:

JSFiddle: http://jsfiddle.net/UgT3x/

for (key in aray) {
    var steve = aray[key];
    console.log(toTitleCase(steve));
    // if you want to change the aray value
    aray[key] = toTitleCase(steve);
}

function toTitleCase(str) {
    return str.replace(/\w\S*/g, function (txt) {
        return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
    });
}