从数组 Javascript 中删除重复项
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Remove duplicate item from array Javascript
提问by Matthew
I'm looking for an easy way of removing a duplicate value from an array. I figured out how to detect if there is a duplicate or not, just I don't know how to "push" it from the value. For example, if you go to the link provided, and then type, "abca" (press return/enter key after each letter).. it will alert "duplicate!"
我正在寻找一种从数组中删除重复值的简单方法。我想出了如何检测是否有重复的方法，只是我不知道如何从值中“推送”它。例如，如果您转到提供的链接，然后键入“abca” （在每个字母后按回车/回车键）.. 它会提示“重复！”
But I also want to figure out how to remove that duplicate from the textarea?
但我也想弄清楚如何从 textarea 中删除重复项？
This is the part that seems to not be working ::
这是似乎不起作用的部分::
sort = sort.push(i);
textVal = sort;
return textVal;
回答by user2668376
Why do it the hard way, it can be done more easily using javascript filter function which is specifically for this kind of operations:
为什么要这样做困难，使用专门用于此类操作的javascript过滤器功能可以更轻松地完成：
var arr = ["apple", "bannana", "orange", "apple", "orange"];
arr = arr.filter( function( item, index, inputArray ) {
return inputArray.indexOf(item) == index;
});
---------------------
Output: ["apple", "bannana", "orange"]
回答by Frank Roth
Based on user2668376 solution, this will return a new array without duplicates.
基于 user2668376 解决方案，这将返回一个没有重复的新数组。
Array.prototype.removeDuplicates = function () {
return this.filter(function (item, index, self) {
return self.indexOf(item) == index;
});
};
After that you can do:
之后你可以这样做：
[1, 3, 3, 7].removeDuplicates();
Result will be; [1, 3, 7].
结果将是；[1, 3, 7].
回答by Ian
These are the functions I created/use for removing duplicates:
这些是我创建/用于删除重复项的函数：
var removeDuplicatesInPlace = function (arr) {
var i, j, cur, found;
for (i = arr.length - 1; i >= 0; i--) {
cur = arr[i];
found = false;
for (j = i - 1; !found && j >= 0; j--) {
if (cur === arr[j]) {
if (i !== j) {
arr.splice(i, 1);
}
found = true;
}
}
}
return arr;
};
var removeDuplicatesGetCopy = function (arr) {
var ret, len, i, j, cur, found;
ret = [];
len = arr.length;
for (i = 0; i < len; i++) {
cur = arr[i];
found = false;
for (j = 0; !found && (j < len); j++) {
if (cur === arr[j]) {
if (i === j) {
ret.push(cur);
}
found = true;
}
}
}
return ret;
};
So using the first one, this is how your code could look:
所以使用第一个，这就是你的代码的样子：
function cleanUp() {
var text = document.getElementById("fld"),
textVal = text.value,
array;
textVal = textVal.replace(/\r/g, " ");
array = textVal.split(/\n/g);
text.value = removeDuplicatesInPlace(array).join("\n");
}
回答by Ja?ck
You can use Array.reduce()to remove the duplicates. You need a helper object to keep track of how many times an item has been seen.
您可以使用Array.reduce()删除重复项。您需要一个辅助对象来跟踪某个项目被看到的次数。
function cleanUp()
{
var textBox = document.getElementById("fld"),
array = textBox.value.split(/\r?\n/g),
o = {},
output;
output = array.reduce(function(prev, current) {
var key = '$' + current;
// have we seen this value before?
if (o[key] === void 0) {
prev.push(current);
o[key] = true;
}
return prev;
}, []);
// write back the result
textBox.value = output.join("\n");
}
The output of the reduce()step can be used directly to populate the text area again, without affecting the original sort order.
该reduce()步骤的输出可以直接用于再次填充文本区域，而不会影响原来的排序顺序。
回答by Blender
You can do this easily with just an object:
您只需使用一个对象即可轻松完成此操作：
function removeDuplicates(text) {
var seen = {};
var result = '';
for (var i = 0; i < text.length; i++) {
var char = text.charAt(i);
if (char in seen) {
continue;
} else {
seen[char] = true;
result += char;
}
}
return result;
}
function cleanUp() {
var elem = document.getElementById("fld");
elem.value = removeDuplicates(elem.value);
}
回答by sivanthi
arr3 = [1, 2, 3, 2, 4, 5];
unique = [];
function findUnique(val)
{
status = '0';
unique.forEach(function(itm){
if(itm==val)
{
status=1;
}
})
return status;
}
arr3.forEach(function(itm){
rtn = findUnique(itm);
if(rtn==0)
unique.push(itm);
});
console.log(unique); // [1, 2, 3, 4, 5]
