Javascript：在字符串后替换单个字符

Question

I'm trying to do something which seems fairly basic, but can't seem to get it working.

I'm trying to strip the characters after the last instance of an underscore.

I have this long Query String:

json_data=demo_title=Demo+title&proc1_script=script.sh+parameters&proc1_chk_make=on&outputp2_value=&demo_input_description=hola+mundo&outputp4_visible=on&outputp4_info=&inputdata1_max_pixels=1024000&tag=&outputp1_id=nanana&proc1_src_compresion=zip&proc1_chk_cmake=off&outputp3_description=&outputp3_value=&inputdata1_description=input+data+description&inputp2_description=bien%3F&inputp3_description=funciona&proc1_cmake=-D+CMAKE_BUILD_TYPE%3Astring%3DRelease+&outputp2_visible=on&outputp3_visible=on&outputp1_type=header&inputp1_type=text&demo_params_description=va+bien&outputp1_description=&inputdata1_type=image2d&proc1_chk_script=off&demo_result_description=win%3F&outputp2_id=nanfdsvfa&inputp1_description=funciona&demo_wait_description=boh&outputp4_description=&inputp2_type=integer&inputp2_id=papapa&outputp1_value=&outputp3_id=nananartrtrt&inputp3_id=pepepe&outputp3_type=header&inputp3_visible=+off&outputp1_visible=on&inputdata1_id=id_lsd&outputp4_value=&inputp2_visible=on&proc1_source=lsd-1.5.zip&inputp3_value=si&proc1_make=-j4+-C+&images_config_file=cfgmydemo.cfg&outputp2_type=header&proc1_subdir=xxx-1.5&proc1_url=http%3A%2F%2Fwww.ipol.im%2Fpub%2Falgo%2F...&inputdata1_image_depth=1x8i&inputp1_id=popopo&inputp1_value=si&inputp2_value=no&demo_data_filename=data_saved.cfg&inputdata1_info=info_lsd&outputp3_info=&inputdata1_image_format=.pgm&outputp1_info=&inputdata1_compress=False&inputp1_visible=on&proc1_id=lsd&outputp4_id=nana&outputp2_description=&outputp4_type=header&outputp2_info=&inputp3_type=float&&tag&inputp4_iddcksmdclk&inputp4_typetext&inputp4_descriptionkldmsclk&inputp4_valueklcdmkl&inputp4_infoclkdmscdl

Now I replace the separator = in separator %24+ and & in +%23+ using fr=fr.replace(/\\&/g,"+%23+");

            Separator


javascript              Mako           

  =                       %24+
  &                       +%23+

But the result is:

   json_data%24+demo_title%24+Demo+title+%23+proc1_script%24+script.sh+parameters+%23+proc1_chk_make%24+on+%23+outputp2_value%24++%23+demo_input_description%24+hola+mundo+%23+outputp4_visible%24+on+%23+outputp4_info%24++%23+inputdata1_max_pixels%24+1024000+%23+tag%24++%23+outputp1_id%24+nanana+%23+proc1_src_compresion%24+zip+%23+proc1_chk_cmake%24+off+%23+outputp3_description%24++%23+outputp3_value%24++%23+inputdata1_description%24+input+data+description+%23+inputp2_description%24+bien%3F+%23+inputp3_description%24+funciona+%23+proc1_cmake%24+-D+CMAKE_BUILD_TYPE%3Astring%3DRelease++%23+outputp2_visible%24+on+%23+outputp3_visible%24+on+%23+outputp1_type%24+header+%23+inputp1_type%24+text+%23+demo_params_description%24+va+bien+%23+outputp1_description%24++%23+inputdata1_type%24+image2d+%23+proc1_chk_script%24+off+%23+demo_result_description%24+win%3F+%23+outputp2_id%24+nanfdsvfa+%23+inputp1_description%24+funciona+%23+demo_wait_description%24+boh+%23+outputp4_description%24++%23+inputp2_type%24+integer+%23+inputp2_id%24+papapa+%23+outputp1_value%24++%23+outputp3_id%24+nananartrtrt+%23+inputp3_id%24+pepepe+%23+outputp3_type%24+header+%23+inputp3_visible%24++off+%23+outputp1_visible%24+on+%23+inputdata1_id%24+id_lsd+%23+outputp4_value%24++%23+inputp2_visible%24+on+%23+proc1_source%24+lsd-1.5.zip+%23+inputp3_value%24+si+%23+proc1_make%24+-j4+-C++%23+images_config_file%24+cfgmydemo.cfg+%23+outputp2_type%24+header+%23+proc1_subdir%24+xxx-1.5+%23+proc1_url%24+http%3A%2F%2Fwww.ipol.im%2Fpub%2Falgo%2F...+%23+inputdata1_image_depth%24+1x8i+%23+inputp1_id%24+popopo+%23+inputp1_value%24+si+%23+inputp2_value%24+no+%23+demo_data_filename%24+data_saved.cfg+%23+inputdata1_info%24+info_lsd+%23+outputp3_info%24++%23+inputdata1_image_format%24+.pgm+%23+outputp1_info%24++%23+inputdata1_compress%24+False+%23+inputp1_visible%24+on+%23+proc1_id%24+lsd+%23+outputp4_id%24+nana+%23+outputp2_description%24++%23+outputp4_type%24+header+%23+outputp2_info%24++%23+inputp3_type%24+float+%23++%23+tag+%23+inputp4_iddcksmdclk+%23+inputp4_typetext+%23+inputp4_descriptionkldmsclk+%23+inputp4_valueklcdmkl+%23+inputp4_infoclkdmscdl

Now I am interested how to replace this = after the value jsondata . Explain: In the Query string there is the string json_data+%23+ and this +%23+ I want replace to = How?

Answer 1

Strip the characters after the last instance of an underscore:

json_data.substring(0, json_data.lastIndexOf("_"));

Replace +%23+ with =

json_data.replace("+%23+", "=");

However, if you're trying to turn all the %xx into what they're supposed to be, you should url decode the string instead. Which would probably have to be something like:

decodeURIComponent((json_data).replace('+', '%20'));