javascript - 根据条件删除数组元素
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javascript - remove array element on condition
提问by dk123
I was wondering how I'd go about implementing a method in javascript that removes all elements of an array that clear a certain condition. (Preferably without using jQuery)
我想知道如何在 javascript 中实现一种方法，该方法删除清除某个条件的数组的所有元素。（最好不使用 jQuery）
Ex.
前任。
ar = [ 1, 2, 3, 4 ];
ar.removeIf( function(item, idx) {
return item > 3;
});
The above would go through each item in the array and remove all those that return truefor the condition (in the example, item > 3).
上面的代码将遍历数组中的每个项目并删除所有return true满足条件的项目（在示例中，项目 > 3）。
I'm just starting out in javascript and was wondering if anyone knew of a short efficient way to get this done.
我刚开始使用 javascript，想知道是否有人知道一种简短有效的方法来完成这项工作。
--update--
——更新——
It would also be great if the condition could work on object properties as well.
如果条件也适用于对象属性，那就太好了。
Ex.
前任。
ar = [ {num:1, str:"a"}, {num:2, str:"b"}, {num:3, str:"c"} ];
ar.removeIf( function(item, idx) {
return item.str == "c";
});
Where the item would be removed if item.str == "c"
如果该项目将被删除 item.str == "c"
--update2--
--更新 2--
It would be nice if index conditions could work as well.
如果索引条件也能正常工作，那就太好了。
Ex.
前任。
ar = [ {num:1, str:"a"}, {num:2, str:"b"}, {num:3, str:"c"} ];
ar.removeIf( function(item, idx) {
return idx == 2;
});
采纳答案by pickypg
You could add your own method to Arraythat does something similar, if filterdoes not work for you.
如果对您Array不起作用，您可以添加自己的方法来做类似的事情filter。
Array.prototype.removeIf = function(callback) {
var i = 0;
while (i < this.length) {
if (callback(this[i], i)) {
this.splice(i, 1);
}
else {
++i;
}
}
};
To me, that's one of the coolest features of JavaScript. Ian pointed out a more efficient way to do the same thing. Considering that it's JavaScript, every bit helps:
对我来说，这是 JavaScript 最酷的特性之一。伊恩指出了一种更有效的方法来做同样的事情。考虑到它是 JavaScript，每一点都有帮助：
Array.prototype.removeIf = function(callback) {
var i = this.length;
while (i--) {
if (callback(this[i], i)) {
this.splice(i, 1);
}
}
};
This avoids the need to even worry about the updating lengthor catching the next item, as you work your way left rather than right.
这避免了甚至担心更新length或捕获下一个项目的需要，因为您向左而不是向右工作。
回答by Klaster_1
You can use Array filter method.
您可以使用数组过滤器方法。
The code would look like this:
代码如下所示：
ar = [1, 2, 3, 4];
ar = ar.filter(item => !(item > 3));
console.log(ar) // [1, 2, 3]回答by Blender
You can use Array.filter(), which does the opposite:
您可以使用Array.filter()，它的作用相反：
ar.filter(function(item, idx) {
return item <= 3;
});
回答by Satoshi Suzuki
You can use lodash.remove
您可以使用lodash.remove
var array = [1, 2, 3, 4];
var evens = _.remove(array, function(n) {
return n % 2 == 0;
});
console.log(array);
// => [1, 3]
console.log(evens);
// => [2, 4]
回答by michal.jakubeczy
Make it a one-liner with arrow function:
使其成为具有箭头功能的单线：
ar = ar.filter(i => i > 3);
回答by PSL
I love these kinds of questions and just a different version from me too... :)
我喜欢这些类型的问题，而且与我的版本不同...... :)
Array.prototype.removeIf = function(expression) {
var res = [];
for(var idx=0; idx<this.length; idx++)
{
var currentItem = this[idx];
if(!expression(currentItem))
{
res.push(currentItem);
}
}
return res;
}
ar = [ 1, 2, 3, 4 ];
var result = ar.removeIf(expCallBack);
console.log(result);
function expCallBack(item)
{
return item > 3;
}
回答by vamsikrishnamannem
simply write the following example if condition could work on object properties as well
如果条件也适用于对象属性，只需编写以下示例
var ar = [ {num:1, str:"a"}, {num:2, str:"b"}, {num:3, str:"c"} ];
var newArray = [];
for (var i = 0, len = ar.length; i<len; i++) {
if (ar[i].str == "b")
{newArray.push(ar[i]);};
};
console.log(newArray);
See the example Live Example
查看示例现场示例
