1. Replace all <b> with <strong>, preserving any existing attributes Match: <(/?)b\b((?:[^>"']| "[^"]*"| '[^']*')*)> Replace: <\1strong\2> eg. <b fdjfkjdk>inikkk</b fdjkfjk> ====> <strong fdjfkjdk>inikkk</strong fdjkfjk> 2. Replace all <b> with <strong>, discarding any existing attributes Match: <(/?)b\b((?:[^>"']| "[^"]*"| '[^']*')*)> Replace: <\1strong\2> eg. <b fdjfkjdk>inikkk</b fdjkfjk> ====> <strong>inikkk</strong> 3. Replace a list of tags (<b> <i> <em> <big>) with <strong>, preserving any existing attributes Match: <(/?)([bi]|em|big)\b((?:[^>"']| "[^"]*"| '[^']*')*)> Replace: <\1strong\3> eg. <b fdjfkjdk>inikkk</b fdjkfjk> <i fff>nihao</i nihao> <em ff>nihao</em nihao> <big ff>nihao</big nihao> =====> <strong fdjfkjdk>inikkk</strong fdjkfjk> <strong fff>nihao</strong nihao> <strong ff>nihao</strong nihao> <strong ff>nihao</strong nihao> 4. Replace a list of tags (<b> <i> <em> <big>) with <strong>, discarding any existing attributes Match: <(/?)([bi]|em|big)\b((?:[^>"']| "[^"]*"| '[^']*')*)> Replace: <\1strong> eg. <b fdjfkjdk>inikkk</b fdjkfjk> <i fff>nihao</i nihao> <em ff>nihao</em nihao> <big ff>nihao</big nihao> =====> <strong>inikkk</strong> <strong>nihao</strong> <strong>nihao</strong> <strong>nihao</strong>