js comma expression

• Results comma expression: taking a last value, as follows

var a=4;
switch (a){ case 2: console.log(2); break; case 1,3,4: console.log(134); break; default: console.log("没有符合条件的值"); break; } // 如果 var a = 1; ------会打印 “没有符合条件的值” // 如果 var a = 2; ------------- 2 // 如果 var a = 3; ------------- 没有符合条件的值 // 如果 var a = 4; ------------- 134 

var i,j,k;
for(i=0,j=0;i<10,j<6;i++,j++){ k=i+j; } console.log(k); // 10 

var i,j,k;
for(i=0,j=0;i<6,j<10;i++,j++){ k=i+j; } console.log(k); // 18 

• Note: the comma operator generally lower priority than the operator, so that the use of the general use of which to wrap parentheses:

var b = (1,2,3); console.log(b); // 结果是 3