replace函数示例

replace( string1, string_to_replace, [ replacement_string ] ) 　　
replace('123123tech', '123'); would return 'tech' 　
两个参数，把123去掉　
replace('123tech123', '123'); would return 'tech'
 两个参数，把123去掉　　　
replace('222tech', '2', '3'); would return '333tech'
三个参数，用3替换2　　
replace('0000123', '0'); would return '123' 　
两个参数 把0去掉　
replace('0000123', '0', ' '); would return ' 123'
三个参数，用空格替换0