迴圈loop筆記

label/goto

var i = 1;
label:
console.log(i)
i++;
if (i <=100){
    goto label
};

do/while

var i = 1;
do {
    console.log (i)
    i++
} while(i <= 100)
do {
    console.log (i)
    i++
    if (i >100){
        break
    }
} while (true)

break vs. continue情況比較

var i = 1;
do {
    console.log (i)
    i++
    if (i <= 1000) {
        break // 跳出整個迴圈
    }
    console.log('i++', i)
} while (i<=100)

console.log('i=', i) // 直接到這

var i = 1;
do {
    console.log (i)
    i++
    if (i <=1000) {
        continue // 跑到下一圈
    }
    console.log('i++', i) // 會忽略掉這行
}while (i<=100)

console.log('i=', i)

while

var i = 1;
while (i <= 100){
    console.log(i++) // 會先log(i)再執行++
};
console.log('i=', i);

for

for (var i = 1; i<=100; i+=2){
    console.log (i)
};

break vs. continue情況比較

for (var i = 1; i<=5; i++){
    if (i === 3) break　// 3就跳掉了只會log出1.2
    console.log (i)
};

for (var i = 1; i<=5; i++){
    if (i ===3) continue　// i=3時不會執行log但仍會執行++
    console.log (i)
};

奇數偶數倍數

取餘數

for (var i = 1; i<=10; i++) {
    if (i % 2) continue　// 只印出偶數，奇數跳掉
    console.log (i)
}

2倍

for (var i = 1; i<=10; i*=2){
    console.log (i) // 1.2.4.8
}

結合陣列

var scores = [10, 24, 34, 42, 51]
var sum = 0
for (var i=0; i<scores.length; i++) {
    sum += scores[i]
}
console.log(sum)