javascript iteration method

every() method

Runs the given function for each item in the array, and returns true if it returns true for each item

let number = [1,2,3,4,5,6,7,8,9,10,11,12,1,31,21];

Example 1:

let everyResult = number.every(function(item,index,array){
    console.log('item:'+item); //item:1
    console.log('index:'+index); //index:0
    console.log('array:'+array); //array:1,2,3,4,5,6,7,8,9,10,11,12,1,31,21
});
console.log(everyResult); // false

Example 2:

let everyResult2 = number.every(function(item,index,array){
    return item>2;
});
console.log(everyResult2); // false

Example 3:

let everyResult3 = number.every(function(item,index,array){
    return item>=1;
});
console.log(everyResult3); // true

some() method

Runs the given function for each item in the array, and returns true if it returns true for any item.

Example 1:

let someResult = number.some(function(item,index,array){
    console.log('item:'+item); //Output every item
    console.log('index:'+index);
    console.log('array:'+array);
});
console.log(someResult); // false

Example 2:

let someResult2 = number.some(function(item,index,array){
    return item>2;
});
console.log(someResult2); // true

Example 3:

let someResult3 = number.some(function(item,index,array){
    return item<0;
});
console.log(someResult3); // false

filter() method

Run the given function for each item in the array, and the return function returns an array of items that are true.

Example 1:

let filetResult = number.filter(function(item,index,array){
    console.log('item:'+item);
    console.log('index:'+index);
    console.log('array:'+array);//Loop out all items
});
console.log(filetResult);// Empty array

Example 2:

let filetResult2 = number.filter(function(item,index,array){
    return item>4;
});
console.log(filetResult2);// (10) [5, 6, 7, 8, 9, 10, 11, 12, 31, 21]

Example 3:

let filetResult3 = number.filter(function(item,index,array){
    return item<1;
});
console.log(filetResult3);//Empty array

map() method

Run the given function for each item in the array, and return the array composed of the results of each function call.

example:

let mapResult = number.map(function(item,index,array){
    return item*2;
});
console.log(mapResult);//(15) [2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 2, 62, 42]

forEach() method

Runs the given function for each item in the array with no return value.

numbers.forEach(function(item,index,array){
    //Do something
});

Posted on Wed, 27 May 2020 12:01:55 -0400 by SpectralDesign.Net