Array object methods commonly used traversal methods & higher-order functions

3、 ... and 、 Common traversal methods & Higher order function

1.for()

Most commonly used for loop , Frequently used array traversal , You can also traverse strings .

const arr = [1, 2, 3]
const str = 'abc'
for (let i = 0; i < arr.length; i++) {
    console.log(arr[i])
    console.log(str[i])
}

2.while() / do while()

while、do while The main functions are , When satisfied while The following conditions , To perform related business . The difference between the two is ,while Will first judge whether the conditions are met , Then perform the tasks in curly braces , and do while It is to perform the task in curly brackets first , To perform while Conditions , Judge whether to execute again next time do Operation inside . in other words  do while At least one operation will be performed .

while( Conditions ){
      perform ...
}
------------
do{
     perform ...
}
while( Conditions )

3.forEach()

Copy a copy to traverse the original array .

• return Cannot terminate loop . But it can play continue effect .

• It doesn't support itself continue And break We can use some and  every To achieve .