javascript 如何从javascript中的foreach循环中删除特定的数组元素
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How to delete specific array elements from within a foreach loop in javascript
提问by Nick
var fruit = ["apple","pear","pear","pear","banana"];
How do I remove all "pear" fruit from this array?
I tried the following, but still one pear remains:
如何从此数组中删除所有“梨”水果？
我尝试了以下方法，但仍然留下一个梨：
for(var f in fruit) {
if ( fruit[f] == "pear" ) {
fruit.splice(f, 1);
}
}
for(var f in fruit) {
document.write(fruit[f]+"<br>");
}
Outputs:
输出：
apple
pear
banana
?What am I doing wrong? Live demo: http://jsfiddle.net/SbxHc/
？我究竟做错了什么？现场演示：http: //jsfiddle.net/SbxHc/
回答by Esailija
var fruit = ["apple", "pear", "pear", "pear", "banana"],
i;
for (i = 0; i < fruit.length; ++i) {
if (fruit[i] === "pear") {
fruit.splice(i--, 1);
}
}
console.log(fruit);
//["apple", "banana"]
回答by Tom
for (var i = fruit.length - 1; i > -1; i--) {
if (fruit[i] == "pear")
fruit.splice(i, 1);
}
回答by Tuan
When you remove items from an array as you iterate over it, you would generally iterate backwards so that the current index doesn't skip over items as you remove them:
当您在迭代数组时从数组中删除项目时，您通常会向后迭代，以便当前索引在您删除项目时不会跳过项目：
var fruit = ["apple","pear","pear","pear","banana"];
var i;
for (i = fruit .length - 1; i >= 0; i--) {
if (fruit [i] === "pear") {
fruit .splice(i, 1);
}
}
console.log(fruit );
回答by raina77ow
If there are plenty of 'wrong' elements in the original array, I suggest at least considering not using in-place array, instead collecting all the 'right' elements into a new array:
如果原始数组中有很多“错误”元素，我建议至少考虑不使用就地数组，而是将所有“正确”元素收集到一个新数组中：
var rightFruits = [];
for (var i = 0, len = fruit.length; i < len; ++i) {
if (fruit[i] !== 'pear') {
rightFruits.push(fruit[i]);
}
}
回答by user278064
var i;
for (i = 0; i < fruits.length; i += 1) {
if (fruits[i] == "pear") {
fruits.splice(i, 1);
i -= 1;
}
}
6.4. Enumeration
6.4. 枚举
Since JavaScript's arrays are really objects, the for instatement can be used to iterate over all of the properties of an array.
Unfortunately, for inmakes no guarantee about the order of the properties, and most
array applications expect the elements to be produced in numerical order. Also, there is still the problem with
unexpected properties being dredged up from the prototype chain.
由于 JavaScript 的数组实际上是对象，因此该for in语句可用于迭代数组的所有属性。不幸的是，for in不能保证属性的顺序，大多数数组应用程序都希望元素按数字顺序生成。此外，仍然存在从原型链中挖掘出意外属性的问题。
Fortunately, the conventional for statement avoids these problems. JavaScript's for statement is similar to that in most C-like languages. It is controlled by three clauses: the first initializes the loop, the second is the while condition, and the third does the increment:
幸运的是，传统的 for 语句避免了这些问题。JavaScript 的 for 语句类似于大多数类 C 语言中的语句。它由三个子句控制：第一个初始化循环，第二个是 while 条件，第三个执行增量：
var i;
for (i = 0; i < myArray.length; i += 1) {
document.writeln(myArray[i]);
}
回答by user278064
You could also use a filter:
您还可以使用filter：
let noPears = fruits.filter(fruit => fruit != 'pear')
回答by Lain inVerse
var i; while ((i = fruit.indexOf("pear")) > -1) fruit.splice(i,1);
Be aware that Array.indexOf is not supported by IE8 and below. -_-
请注意 Array.indexOf 不受 IE8 及以下版本的支持。-_-
回答by rodrigo-silveira
Why not iterate the list backwards? That way, when you delete an element from the list and the length changes, it doesn't break the loop logic:
为什么不向后迭代列表？这样，当您从列表中删除一个元素并且长度发生变化时，它不会破坏循环逻辑：
var fruit = ["apple","pear","pear","pear","banana"];
for (var i = fruit.length - 1; i >= 0; i--) {
if (fruit[i] === "pear") {
fruit.splice(i, 1);
}
}
console.log(fruit); // ["apple", "banana"]
回答by Jobacca
If it doesn't care to iterate reverse, you can use a combination of while and array's pop-function
如果不关心反向迭代，可以结合使用while和array的pop-function
var daltons = [
{ id: 1, name: "Joe" },
{ id: 2, name: "William" },
{ id: 3, name: "Hyman" },
{ id: 4, name: "Averell" }
];
var dalton;
while (dalton=daltons.pop()) {
console.log(dalton.name);
}
console.log(daltons);
回答by Dan Barzilay
for(var f in fruit) {
if ( fruit[f] == "pear" ) {
fruit.splice(f-1, 1);
}
}
for(var f in fruit) {
document.write(fruit[f]+"<br>");
}
enjoy
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