Determine the number of odd and even numbers in the numeric array
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Array operation</title>
</head>
<body>
<script type="text/javascript">
var arr=[3,1,2,2,1,3,1];
var sum=[];
var res=[];
var count=0;
var temp;
for(var i=0;i<;i++){
if((arr[i])==-1){
(arr[i]);
}
}
for(var i=0;i<;i++){
for(var j=0;j<;j++){
if(arr[j]==res[i]){
count++;
}
}
(count);
count=0;
}
(res);//[3,1,2]
for(var i=0;i<;i++){
var str=(sum[i]%2==0)?"even":"odd number";
(res[i]+"It appears"+sum[i]+"Second-rate");
(res[i]+"It appears"+str+"Second-rate");
}
</script>
</body>
</html>
Alibaba written test - array operation - find out different elements in two arrays
<script type="text/javascript">
function diff(arr1,arr2){
var ress = [];
var arr = (arr2);
for(var i=0,len=;i<len;i++){
if(((arr[i])>=0 && (arr[i])<0) || ((arr[i])<0 && (arr[i])>=0)){
(arr[i]);
}
}
return ress;
}
var arr1 = [1,2,3,5,7,6];
var arr2 = [1,2,5];
var res = diff(arr1,arr2);
(res);//[3, 7, 6]
</script>
Array deduplication
Method 1
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Array deduplication01</title>
</head>
<body>
<script type="text/javascript">
//Add method to array prototype = function(){
var arr = [];
for(var i=0,i=;i<len;i++){
if((this[i]) == -1){
(this[i]);
}
}
return arr;
};
([1,2,3,2,5,6,3].unique());//[1, 2, 3, 5, 6]
</script>
</body>
</html>
Method 2
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Array deduplication02</title>
</head>
<body>
<script type="text/javascript">
= function(){
var n = {},
r=[]; //n is a hash table, r is a temporary array for(var i = 0; i < ; i++) //Transfer the current array {
if (!n[this[i]]) //If there is no current item in the hash table {
n[this[i]] = true; //Save hash table (this[i]); //Push the current item of the current array into the temporary array }
}
return r;
}
([1,2,3,2,5,6,3].unique());//[1, 2, 3, 5, 6]
</script>
</body>
</html>
Method 3
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Array deduplication</title>
</head>
<body>
<script type="text/javascript">
= function(){
var arr = [this[0]];//Result array for(var i=1;i<;i++){//Start the second item if((this[i]) == i){
//If the i-th item of the current array appears in the first time in the current array is not i, then it means that the i-th item is repeated and ignored. Otherwise, save the result array (this[i]);
}
}
return arr;
}
([1,2,3,4,2,3,4].unique());// [1, 2, 3, 4]
</script>
</body>
</html>
Method 4
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>filter</title>
<link rel="stylesheet" href="">
</head>
<body>
<script type="text/javascript">
var arr = [4,5,3,2,3,4,5,1];
function fn(num){
var res = (function(item,index,array){
return (item) === index;//(item) will return the location where the element first appears in the array //For elements that appear multiple times, false will be returned in other cases except for the first time. });
return res;
}
(fn(arr));//[4, 5, 3, 2, 1]
</script>
</body>
</html>
Method 5
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>Object Use objects as hash table</title>
<link rel="stylesheet" href="">
</head>
<body>
<script type="text/javascript">
function unique(a) {
var obj = {};
return (function(item) {//filter will return a member of the item that is true return (item) ? false : (obj[item] = true);
});
}
var a = [1, 1, 3, 2, 1, 2, 4];
var res = unique(a);
(res); // [1, 3, 2, 4]
</script>
</body>
</html>
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