js selected values from another array present in an array
Here screened from the present value of arr arr1, arr2 result array for the screening
let arr=["1","2","3","4","5"];
let arr1=["2","1","4","6"];
let arr2=[];
1: Direct comparison value
1, using a for loop
for(let i=0;i<arr.length;i++){
for(let j=0;j<arr1.length;j++){
if(arr[i]==arr1[j]){
arr2.push(arr1[j]);
}
}
}
2, using forEach loop
arr.forEach(item=>{
arr1.forEach(element=>{
if(item==element){
arr2.push(item);
}
})
});
3, the filter using filter
arr2=arr.filter(checkAdult);
function checkAdult(age) {
for(let i=0;i<arr1.length;i++){
if(age==arr1[i])
return true
}
};
4、for……of
for(let i of arr){
for(let j of arr1){
if(i==j){
arr2.push(j);
}
}
}
Second way: indexOf ()
1、for()
for(let i=0;i<arr.length;i++){
if(arr1.indexOf(arr[i])>=0){
arr2.push(arr[i]);
}
}
2、forEach()
arr.forEach(item=>{
if(arr1.indexOf(item)>=0){
arr2.push(item);
}
});
3, the filter using filter
arr2=arr.filter(checkAdult);
function checkAdult(age) {
if(arr1.indexOf(age)>=0){
return true
}
};
4、for……of
for(let i of arr){
arr1.indexOf(i)>=0 && arr2.push(i);
}
Three ways: includes ()
1、for()
for(let i=0;i<arr.length;i++{
arr1.includes(arr[i])&&arr2.push(arr[i]);
}
2、forEach()
arr.forEach(item=>{
arr1.includes(item)&&arr2.push(item);
});
3、filter()
arr.filter(item=>{
arr1.includes(item)&&arr2.push(item);
});
4、for……of
for(let i of arr){
arr1.includes(i)&&arr2.push(i);
}
Results: arr2 = [ "1", "2", "4"]