复制代码 代码如下:

console.log('----1----')

console.log('12' + '34')//'1234'

console.log('12' + 34 )//'1234'

console.log(12 + '34')//'1234'

console.log(12 + 34 )//46

console.log('----2----')

console.log(+'12' + '34')//'1234'

console.log(+'12' + 34 )//46

console.log(+12 + '34')//'1234'

console.log(+12 + 34 )//46

console.log('----3----')

console.log(-'12' + '34')//'-1234'

console.log(-'12' + 34)//22

console.log(-12 + '34')//'-1234'

console.log(-12 + 34)//22

console.log('----4----')

console.log('12' - '34')//-22

console.log('12' - 34)//-22

console.log(12 - '34')//-22

console.log(12 - 34)//-22

console.log('----5----')

console.log(+'12' - '34')//-22

console.log(+'12' - 34)//-22

console.log(+12 - '34')//-22

console.log(+12 - 34)//-22

console.log('----6----')

console.log(-'12' - '34')//-22

console.log(-'12' - 34)//-22

console.log(-12 - '34')//-22

console.log(-12 - 34)//-22

javascript中字符串连接的同时数字相加

document.write("<img src='images/" + i + 1 + ".jpg'>")

假如i=1，以上代码输出为<img src='images/11.jpg'>

如果想输出为2.jpg，应该这样写

document.write("<img src='images/" + (i+1) + ".jpg'>")