“ AppendChild”在函数内部不起作用吗？

Question

"use strict";

Object.prototype.$ = function( selector ) {
    var sel = selector;
    if ( typeof sel == "string" ) {
        var elem = document.querySelectorAll( sel );
        if ( elem.length == 1 ) return elem[0];
        else if ( elem.length > 1 ) return elem;
    } else
        throw new Error( "Can't find element!" );
}

Object.prototype.crElem = function( e ) {
    var name  = document.createElement( e.name );
    var place = $( e.place );
    if ( e.value == undefined ) {
        place.appendChild( name );
    } else if ( e.value ) {
        name.innerHTML = e.value;
        place.appendChild( name );
    }
}

crElem({
    name: "button",
    place: ".slide"
});

in the console comes out this error: " Uncaught TypeError: place.appendChild is not a function "

Answer 1

Your $() function returns an array, and then you try to call .appendChild() on that. Of course that won't work. You need to call it on a specific element, like place[0].appendChild(name) . Also, what will you do when $() returns several elements?