我的删除功能有什么问题？

Question

Array.prototype.remove = function (obj) {
    for(var i = 0; i < this.length; i++) {
        if(this[i] === obj) {
            if (i == this.length) {
                this[i] = null;
            } else {
                for(var j = i; j < this.length-1; j++) {
                    this[j] = this[j+1];
                }
                delete this[j]; // updated from this[j] = null; still not working.
            }
        }
    }
    return this;
};

calling it with:

write("ARRAY TEST = " + [22, 33, 44].remove(33).remove(22));

..it prints:

44,,

Why this 2 commas and how to fix my remove function to remove the commas as well?

Answer 1

delete on an Array will not remove the element, it will set it to undefined . And since undefined when printed results in an empty string, that explains the results of write() .

You need to use splice() to remove the element. If you combine it with indexOf (you may need to define it for older browser) you get a pretty short function:

Array.prototype.remove = function (obj) {
    this.splice(this.indexOf(obj), 1);
    return this;
}

PS: I'm not an advocate of expanding native prototypes...

Answer 2

将项设置为null会在数组中留下一个项（但它是一个空项），这就是为什么你仍然看到逗号的原因。

Answer 3

As previously mentioned, deleting or setting the item to null still leaves the item in the array. What you want to use is Array.splice

Here's an implementation that should work:

Array.prototype.remove = function (obj) {
    for(var i = 0; i < this.length; i++) {
       if(this[i] === obj)
       {
           this.splice(i,1);
           break;
       }       
    }
    return this;
};

Answer 4

You don't remove the elements from the array you just set them to null. If you need inspiration look at this remove method. It's by index and not by element.

http://ejohn.org/blog/javascript-array-remove/

try:

Array.prototype.remove = function (obj) {
    for(var i = 0; i < this.length; i++) {
        if(this[i] === obj) {
            if (i == this.length) {
                this.splice(i,1);
            } else {
                for(var j = i; j < this.length-1; j++) {
                    this[j] = this[j+1];
                }
                this.splice(j,1);
            }
        }
    }
    return this;
};

Answer 5

Array.prototype.remove = function (obj) {
    for(var i = 0; i < this.length; i++) {
        if(this[i] === obj) {
            if (i == this.length) {
                #this[i] = null;
                delete this[i];
            } else {
                for(var j = i; j < this.length-1; j++) {
                    this[j] = this[j+1];
                }
                #this[j] = null;
                delete this[i];
            }
        }
    }
    return this;
};

Pretty sure that is what you want