/^/\/\/

/^\\/

<script>
var s= "\\wowo\\wcxzcxzo";
var w=s.replace(/(^[\\\\])(.*?)/ig,"aaa"+"$2")
alert(w)
</script>

<script>
var s= "\\wowo\\wcxzcxzo";
var w=s.replace(/(^[\\])(.*?)/,"aaa"+"$2")
alert(w)
</script>

<script>
var s= "\\wowo\\wcxzcxzo";
var w=s.replace("\\","aaa")
alert(w)
</script>