如何从JavaScript数组中删除空元素?
有没有简单直接的方法,还是必须手动循环并逐个删除?
如何从JavaScript数组中删除空元素?
有没有简单直接的方法,还是必须手动循环并逐个删除?
function pack(arr) { // remove undefined values
let p = -1
for (let i = 0, len = arr.length; i < len; i++) {
if (arr[i] !== undefined) { if (p >= 0) { arr[p] = arr[i]; p++ } }
else if (p < 0) p = i
}
if (p >= 0) arr.length = p
return arr
}
let a = [1, 2, 3, undefined, undefined, 4, 5, undefined, null]
console.log(JSON.stringify(a))
pack(a)
console.log(JSON.stringify(a))
使用正则表达式过滤无效条目
array = array.filter(/\w/);
filter + regexp
"----"
(带有非单词字符的字符串)。 - VLAZ这是我清理空字段的解决方案。
从费用对象开始: 获取仅可用属性(使用map) 过滤空字段(使用filter) 将结果解析为整数(使用map)
fees.map( ( e ) => e.avail ).filter( v => v!== '').map( i => parseInt( i ) );
var a = [{a1: 1, children: [{a1: 2}, undefined, {a1: 3}]}, undefined, {a1: 5}, undefined, {a1: 6}]
function removeNilItemInArray(arr) {
if (!arr || !arr.length) return;
for (let i = 0; i < arr.length; i++) {
if (!arr[i]) {
arr.splice(i , 1);
continue;
}
removeNilItemInArray(arr[i].children);
}
}
var b = a;
removeNilItemInArray(a);
// Always keep this memory zone
console.log(b);
这里是一个使用可变行为和ES2015箭头函数表达式的示例:
Array.prototype.clean = function() {
var args = [].slice.call(arguments);
return this.filter(item => args.indexOf(item) === -1);
};
// Usage
var arr = ["", undefined, 3, "yes", undefined, undefined, ""];
arr.clean(undefined); // ["", 3, "yes", ""];
arr.clean(undefined, ""); // [3, "yes"];
// recursive implementation
function compact(arr) {
const compactArray = [];
//base case
if(!arr.length) return []
if(typeof arr[0] !== "undefined"
&& arr[0]!==null && arr[0] !== " " &&
arr[0]!== false &&
arr[0]!== 0){
compactArray.push(arr[0]);
}
return compactArray.concat(compact(arr.slice(1)))
}
compact([1,0,false,null,undefined,"banana"])`
很好...非常好 我们也可以像这样替换所有数组值
Array.prototype.ReplaceAllValues = function(OldValue,newValue)
{
for( var i = 0; i < this.length; i++ )
{
if( this[i] == OldValue )
{
this[i] = newValue;
}
}
};
1. replace "__" or more with just one "_",
2. replace preceding "_" with nothing "" and similarly
3. replace and ending "_" with nothing ""
然后使用数组 "split" 来创建一个清理过的数组:
var myArr = new Array("","","a","b","","c","","","","","","","","","e","");
var myStr = "";
myStr = myArr.join("_");
myStr = myStr.replace(new RegExp(/__*/g),"_");
myStr = myStr.replace(new RegExp(/^_/i),"");
myStr = myStr.replace(new RegExp(/_$/i),"");
myArr = myStr.split("_");
alert("myArr=" + myArr.join(","));
...或者在一行代码中实现:
var myArr = new Array("","","a","b","","c","","","","","","","","","e","");
myArr = myArr.join("_").replace(new RegExp(/__*/g),"_").replace(new RegExp(/^_/i),"").replace(new RegExp(/_$/i),"").split("_");
alert("myArr=" + myArr.join(","));
...或者,扩展数组对象 :-
Array.prototype.clean = function() {
return this.join("_").replace(new RegExp(/__*/g),"_").replace(new RegExp(/^_/i),"").replace(new RegExp(/_$/i),"").split("_");
};
var myArr = new Array("","","a","b","","c","","","","","","","","","e","");
alert("myArr=" + myArr.clean().join(","));
这是另一种方法:
var arr = ["a", "b", undefined, undefined, "e", undefined, "g", undefined, "i", "", "k"]
var cleanArr = arr.join('.').split(/\.+/);
这样做怎么样?
// Removes all falsy values
arr = arr.filter(function(array_val) { // creates an anonymous filter func
var x = Boolean(array_val); // checks if val is null
return x == true; // returns val to array if not null
});
var a = [,,]
和var a = [undefined, undefined]
之间存在区别。前者是真正的空数组,而后者实际上有两个键,但值为undefined
。 - Alnitaknull
/undefined
是更好的实践。例如,如果你的null
来自于使用map
函数映射另一个数组时,对于某些元素返回null
,那么在运行map
之前尝试使用Array.filter
过滤掉这些元素。这样可以使你的代码更易读/自我记录。显然,这并不适用于每种情况,但它可以应用于很多情况。 - Luke Redmore