stringCharAt.js - mozsearch

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assertEq("foo".charAt(-123), "");

assertEq("foo".charAt(-1), "");

assertEq("foo".charAt(0), "f");

assertEq("foo".charAt(1), "o");

assertEq("foo".charAt(2), "o");

assertEq("foo".charAt(3.4), "");

assertEq("foo".charAt(), "f");

assertEq("".charAt(), "");

assertEq("".charAt(0), "");

assertEq("abc\u9123".charAt(3), "\u9123"); // char without unit string

/* Inferred as string.charAt(int). */

function charAt1(x) {

    return "abc".charAt(x);

assertEq(charAt1(-1), "");

assertEq(charAt1(0), "a");

assertEq(charAt1(1), "b");

assertEq(charAt1(2), "c");

assertEq(charAt1(3), "");

assertEq(charAt1(1234), "");

/* Inferred as string.charAt(double). */

function charAt2(x) {

    return "abc".charAt(x);

assertEq(charAt2(-1.3), "");

assertEq(charAt2(-0), "a");

assertEq(charAt2(2), "c");

assertEq(charAt2(2.3), "c");

assertEq(charAt2(3.14), "");

assertEq(charAt2(NaN), "a");

/* Test ropes. */

function charAt3(s, i) {

    var s2 = "abcdef" + s + "12345";

    return s2.charAt(i);

assertEq(charAt3("abcdef", 14), "3");

assertEq(charAt3("a" + "b", 1), "b");

assertEq(charAt3("abcdefg" + "hijklmnop", 10), "e");

/* Other 'this'. */

var arr = [1, 2];

arr.charAt = String.prototype.charAt;

assertEq(arr.charAt(1), ",");