javascript - jQuery for(x in y) 循环

Question

在下面的代码中，变量“key”没有大写，即使任何其他变量(例如 steve[j])在替换“key”时都会大写"在对函数 capitaliseFirstLetter() 的调用中。

有人能告诉我为什么吗？

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)

字符串对象按值传递给函数。所以它没有改变你应该重新分配值(value)